I guess you have seen the -єть in some more verbe by now. It is the present tense for he/she/it (like -s in English). Now, the suffix -ся is attached to that. This makes a verb reflexive, like -se in Spanish, sich in German or się in PL :)
No. Laughing and smiling are two different things in English and all the languages I know. I have checked Ukrainian on Google Translate and it uses the word "сміятися" for "smile". Out of curiosity, does your native language use the same word for "smile" and "laugh" ?
Some slavic languages use similar sounding words like smíchat, which can mean smile or laugh depending on the language or context, so while smiling/,laughing are different in English, I know where that dude is coming from