You really have difficult questions, seems you are deep into the grammar ^_^ The easiest explanation can be, when in the context of a sentence you can mean "own and not others" while you have kinda possessive relation to the thing or even more, positive possessive relation. Svoj is gender nonsensitive word. Svoj can mean - my own, your own, his/her/their own. It's obvious that my sister is moja sestra and she is only mine, not your sister, (because we are not brothers), so I do not need to specify "s mojou sestrou", rather use general word "svoj", so that's why so svojou sestrou. ______________ If I wrote "you often draw pictures with your sister", does that become "často kreslíš obrazky so svojou sestrou"? Yep, you got it. If I am asking about your sister, so we know it is your sister and nobody's else, just your one - this is what is meant by mean "positive possessive relation" ^_^ ______________ ============== In English I think there is not any equivalent to the word svoj, as it is said, svoj is used with all grammatical persons, let me give you some examples of using svoj: I will just take MY THINGS and go home. -> Len si zoberiem SVOJE VECI a pôjdem domov. (you take just your own things and not others', you can say: Len si zoberiem MOJE VECI a pôjdem domov. It's the same meaning, but to our ears "svoje" fits better) (English phrase) It's not your business. (Literally in Slovak: Take care about YOUR THINGS) -> Staraj sa o SVOJE VECI. (so take care about your own business and not mine not others, you can also say: staraj sa o tvoje veci, it's also understandable, but to our ears svoje fits better again) Everybody has HIS/HER OWN troubles. -> Každý máme SVOJE starosti. (like: life is not easy and everyone has some annoying stuff in the life which is bothering him/her self alone, not others) If you are at interview, they may ask: Introduce us YOUR OWN ideas. -> Predstavte nám svoje nápady. (Here svoje means "your own", you can use vaše nápady. But while you have possession or relation to that (those are your own ideas not others ones), so they rather say svoje nápady than vaše nápady) A lot of other examples and also explanations of this word you can find here: http://slovniky.juls.savba.sk/?w=svoj&c=69c4

Slovak is not my native language but we have same roots of language :) Always when you speak about yourself things to do, you always say svojou or something like that, but I just know you dont say mojou :)) I hope it helped you little ;))