What does get y cómo se usa, aun no lo entiendo bien. mean?

See a translation

get has a large number of colloquial meanings, for us DAR in Spanish is like this (though they are not really related, both have tons of uses). Here are some major ones.

get into it -> hacer con gusto;
Maybe it was a good book, but I couldn't get into it. No me gusta.

get mad -> ponerse enfadado / molesto etc.
Don't get mad, but I crashed your car. -> No te pongas enfadado, pero..

get around it -> evitar
That rule is stupid, how can I get around it? Cómo puedo evitarla.

get outside of -> comer (Inglaterra)
Here's your pizza! Get outside of that! Cometela.

get laid, get some -> tener sexo
I hope I get laid tonight. -> espero que tenga sexo

get it -> entender
I don't get it. Can you explain it again? -> no lo entendio.

get over it -> superar
It;s sad that your dog died but you will get over it. -> Lo superaré.

get through it -> pasar, implica algo difícil, aprobar
This course is hard but you can get through it. -> puedes aprobarlo

get on it -> prestar atención, dedicar, ponerse
I will get on that project tomorrow. -> Me pongo con este proyecto mañana

HTH
Saludos