I think you're confusing או with -ו.
אמא או אבא
ima o aba
mother or father
mother and father
And on that second part: good question. I think they're trying to do that with "אבא בא" and "האם אהבה באה" etc., although it doesn't look like it's working for everyone. I recommend looking up a chart or busting out some flashcards. [2019/03/25]
I learned the Hebrew alphabet before doing the duolingo course and it helped a lot Aleph - Glottal Stop (Uh), sound depends on niqqud- א Bet - B with daghesh, V without - ב Gimmel - G - ג Dalet - D - ד Hey - H, closed end - ה Vav - V, some niqqud = O, U - ו Zayin - Z - ז Het - Hard H - ח Tet - T - ט Yod - Y, niqqud = I - י Kaf - K with daghesh, Het sound without - כך Lamed - L - ל Mem - M - מם Nun - N - נן Samekh - S - ס Ayin - Voiced Pharyngeal Fricative (if anyone knows what that even means), vowel sound depends on niqqud like aleph - ע Pey -P with daghesh, F without - פף Tsade - Ts, Tz - צץ Qof - Q, K - ק Resh - R - ר Sin, Shin - S with daghesh on left, Sh with daghesh on right - ש Tav - T with daghesh, Th without - ת Some letters have a sofit form, or ending form, when they are at the end of a word - Those are the double letters up in the alphabet. Niqqud are "vowel points", which when put around a letter, make the letter say its sound plus the niqqud sound (Bet + A niqqud = Ba, Aleph + E niqqud = E). Uh Niqqud is line under letter, Ah niqqud is T under letter, Eh niqqud is two dots under, Ey is three dots in triangle, Oh is dot upper left next to vav, U is dot middle left next to vav or three dots like rotated … under letter. Daghesh is dot in letter that determines initial letter sound. Unfortunately, Duolingo does not have niqud or daghesh, which are learning symbols. Hope this helps :) And only things with - are linked in this post not things with space