What does Garage Band even DO? :/

So many sleepless nights… so many apps to discover… So, what *is* Garage Band? As a kid who grew up with her musician-slash-radio-presentor father, surrounded by boxen and boxen of records and *cassettes* and weird and wonderful musicians and DJs, and as a result I have what my Dad and his band and other people have said is ‘perfect pitch’, which would be good if I could play any instrument other than my vocal chords (which I did do for several years, in the Choir at school, but after school and I had a mutual breakup I’ve not done any singing, except in the car or at hip-hop gigs, and that becomes a confidence spiral, not helped by having developed this whole ‘I don’t *want* to leave the house and have friends - I want to stay home with my cats and my husband, preferably with some crosswords and a book and a quality co-op videogame’ thing. The handful of friends and family I’m still in touch after the last five years - TMI for now - have each independently mentioned that the way I at least try to express to them what it’s like for me (if they ask - I’m not soliciting attention - would much rather isolate myself from everyone I care about, for their safety), being who I am and still battling 5+ diagnoses plus the Demagorgon, blah blah they each think that some of the texts I’ve sent when I’m feeling really pathetic ‘pan like lyrics’ and ‘would be a great song’… and given that I don’t have the money to hire the London Symphony Orchestra (even if I *was* stoned, which I’m most certainly not!!! I thought I should find some software to learn how to write music, not just words. But I don’t have any audio gear or a music programme except for this Garage Band thing plus I have a clip-on Rode mini mic and a couple of super-powerful (gaming powerful) computers and I have never opened Garage Band, because they are PCs, and this iPhone box *said* it contained an iPhone, but actually contained a mountain lion. The mountain lion in this scenario represents Garage Band. I do not know what it is, and that makes me anxious. What does it doooo? Should I know anything before I look at it? Will Apple own the rights to anything I make while using it? Is it even worth trying it before I move to something else? I have no idea what my music will be like if I use Garage Band, so can it cope with total n00bies who most-recently made tracks on the (then-new) Propellerhead programme? And does it autotune? I’ve *just* had Whooping Cough.