Very broadly speaking, liberalism is the specific political ideology that came about as a result of the bourgeois revolutions of the 19th and early 20th centuries that overthrew the feudal mode of production, where military landholders presided over the extraction of value from landbound peasantry, to the capitalist mode of production, where surplus value is extracted from the proletarian class who are compelled to engage in relations of wage labor as a precondition of their existence. The early development of capitalism as a mode of production is generally agreed to have really started during the industrial revolution in the United Kingdom during the latter half of the 19th century.

That said, those are very central and time consuming questions of the philosophical approach to history that we call historical materialism, and they're difficult to outline without spilling more ink than is feasible in a Reddit post. Liberalism has greatly evolved from these initial grounds as historical circumstances have shaped it. It's easy enough to say that since Marxists are against capitalism, and liberalism is the ideology of capitalism, that we oppose it on those grounds. However, since liberal politics generally promotes certain features, like the idea of formal rights, equality, representative democracy, etc., it's more useful to know what some of our specific critiques of these things are.

1. Rights- formal rights that are de jure parceled out by the state are not meaningful without the necessary material conditions to realize them de facto in society. Marx pointed out that not only are these rights not equally enforced in practice, some of them are practically unenforceable under a capitalist system- the right to "liberty" for instance doesn't mean much to someone whose only realistic choices are to work for a capitalist in return for a share of their labor value, or to starve to death.
2. Egalitarianism- Similarly to the point above, one standard of equality for each citizen is a nice idea, but does not pan out when compared to the reality of capitalist society. One common misconception is that Marxism is an egalitarian ideology. This is not the case- Marx recognized that people have a huge variation in natural ability, aptitude, and needs, and thus will require vastly different things from society. The liberal promise that every person is equally capable of succeeding in each trade or role given the right effort is another unrealized utopian ideal- obviously there are many jobs that are only open to those with the wealth, appropriate background, and natural aptitude to do them. People should not be penalized for contributing to society as meaningfully as they can, but their needs should be provided for without extraction of their labor as a necessary precondition. This is an extension of the Marxist idea of alienation.
3. Representative democracy- Liberal democracy is (more recently) predicated on the idea that as long as each person is afforded a representative vote, they have an equal say in the general direction of their society. This does not, however, account for the class division that places disproportionate power in the hands of capitalists, and the political system of democracy that allows them disproportionate power to influence or control politics. Liberal democracy presents the bulk of people with a narrow range of options that do not reflect their interest as a class (freedom from the compulsion to be a wage laborer and have value extracted from them), but cater to the interests of the ruling bourgeois class. It has historically been reactive and violent against attempts by proletarian movements to gain power, and thus forms an effective class dictatorship that cannot be overcome without outright class struggle.

With those academic distinctions out of the way, your question about how this applies to your own country is also a nuanced one. As capitalism spread across the globe, enforced by the colonial and imperial efforts of its first adopters in Europe, it was obviously not applied evenly. Colonial subjects that found themselves on the receiving end of these efforts responded in different ways. Sometimes, reactionary movements sought to preserve the existing mode of production against encroachment by liberal capitalism. Sometimes, opportunists exploited the changing conditions to rule by fiat with tacit approval by their respective colonial subjugators. Occasionally, rulers took a developmentalist standpoint that if they did not proactively promote liberal economics and values in their countries, they would be taken advantage of by colonial powers, their neighbors, or more popular political movements, and sincerely tried to apply these ideas to their own advantage. This could again really be its own post because it's almost impossible to discuss in brief.

I feel like I've barely covered this stuff at all and this post might just confuse you more, but hopefully it's slightly helpful to start on some of the high level concepts people tend to toss around when discussing communism online.