That I’ve unwisely installed some bad software and I should delete it, as recommended.

Do you feel like you understand what “hacked” even means? If so: a phone is a little computer. If not… I donno. I guess you should give a bit more story about why you’re interested in “hacking” and yet know so little about it? Something that makes it more interesting to reply.

For basic questions, why wouldn’t you start with Wikipedia, which is an excellent resource? https://en.wikipedia.org/wiki/Phone_hacking