N3
てもかまわない
It doesn't matter if, I don't mind
アルバイト募集中。未経験者でも構いません。
Hiring part time workers. It doesn't matter if you are not experienced.
Explanation
「～てもかまわない」 means 'it's fine even if...' or 'I don't mind', giving permission or showing you don't care. Use the 「て」 form of verbs and adjectives (「でも」 for nouns and na-adjectives): 「ここに座ってもかまいません」 (You may sit here, I don't mind). It is close to 「～てもいい」, but literally it says 'it won't bother me', so it is politer and has no feeling of granting a favour. The negative 「なくてもかまわない」 means 'it's fine not to...'.
Mixed up with
「てもいい」 can sound a bit superior, like permission from above. 「てもかまわない」 stresses 'I personally don't mind', and is often used to politely accept a small request.
When asking an elder or a customer for permission, 「～てもかまいませんか」 is a bit casual. In business, 「～てもよろしいでしょうか」 is more fitting.