"They are mother and father."
Translation:Они мама и папа.
Russian "а" as a conjunction cannot be translated directly. Most often it means "but" (however "but" is translated more often as "но"), but sometimes it means "и" when it joins two sequent sentences in one: "я иду в магазин, а ты [идешь] домой" - "I'm going to a store and you're going home", "я вижу море, а дальше [я вижу] землю", in such cases it can be omitted or replaced with "и". You have to get used to this special conjunction.
"ь" is the soft sign. It indicates the palatalization of the preceding consonant, i.e. a slight pronunciation difference that is hard to pick up on the duolingo audio.
"ы" is a vowel, closer to "i" in "ill," but not quite like anything in English. By comparison, "и" is more like "ee" in "meet."