My parents are gardeners so I’ve been learning from them. I think a good starting point is herbs and some leafy because they are easier to grow and don’t need a lot of attention. Try to grow stuff that you actually eat, like I would grow parsley, coriander and spinach because I eat them nearly weekly.
Some seeds/seedlings I buy from the store but you can also get some from the fruit and veg you buy, I bought some chillies and rockmelon/cantaloupe, sorted out the seeds and dried them. Make sure the seeds you buy are in season e.g. cucumbers and tomatoes in summer. The info should have this info on the plant tag/packet and on the internet of course.
Another thing you need to know is that preparing the soil is important
make sure the soil is loose - dig it up and break up chunks with a shovel
add compost then you can plant your seeds/seedlings!
I highly recommend CaliKim29 on youtube, she’s taught me a lot