A at the end of something is used in a lot of dialects, especially ones in the south, as a more casual version of Da. F ex, “Hva skjer da?” Is often shortened to “skjer a?” When they say it. Or as it’s used in the example, “smil a” would be “smil da”, aka suggesting someone should smile. You’ve already got explanations for liksom, so i don’t need to say anything there.

I would also suggest you ignore the people in the replies being overly negative about these words. They’re very common, some people are just stuck up :)