My polish girfriend propose me weird game.she is bossy in our relationship.

hi my friend give me that webside he told me that here i can get good advise,Hi im irish,and i am with polish girlfriend,we love each other,she dominate in our relationship.last time she told me that she wants "play"with me dominnant and submissive.yestarday i found in her wardrobe collar,leash.i just want ask what can i expect from her?do you play in THAT sometimes with your partners?