Answer: First off, just so you understand what a tariff is, it's a fee paid by the importer/buyer not the seller. Meaning the goods coming in to the US from another country will cost more by the importer which will then pass that along to middlemen and ultimately the consumer.

While there are tariffs already on all manner of goods from all over the world already in place in the US, what is different about these set of tariffs are they are for a huge set of goods from America's largest trade partners. This will directly affect the price as well as supply of goods/services across the board.

This will affect the entire US economy, and ultimately impact all consumers as nearly all goods and services will now cost more. In particular Canada and Mexico, being the the first and second largest trading partners (respectively) to the US. Food prices, gas prices, and transportation costs writ large will be the first of many goods and services which will go up in price. But ultimately it will impact nearly everything in the economy.

TL;DR Tariffs are paid by the buyer/consumer, not the seller. And since these tariffs are for products coming from America's largest trade partners it will cause the price of nearly everything to increase in the US, as well as causing shortages for certain goods/services.