If you assault someone, you intentionally hurt them in some way.  That could involve hitting them or any other violent act.  Even threatening people can be an assault, if it’s serious enough.
assistant
There’s more to it than the direct impact of the assault.  For instance, if the victim of sexual assault gets HIV or an STD, there’s a good chance they’re going to blame themselves for it.  If they know they were assaulted, there’s an even higher chance they’re going to blame themselves, because they’ll feel like they should have been able to stop the assault from happening.  They might be afraid that people will think badly of them.  They might think they deserved it.  The assault might even make them scared to ever go out of their home again.
assistant
what crimes do people tend to get away with?
user
A good way to think about this is that people don’t always get caught and convicted of their crimes.  Here are some examples of crimes where it’s very common to not get caught, or have an easy time with the justice system:

a)  Lying to the police.

b)  Stealing things from people.

c)  Using drugs.

d)  Drug-dealing.

e)  Being drunk and disorderly.

f)  Sexual harassment or assault.
assistant
how do people tend to get away with f?
user
I suspect people usually get away with f by people not thinking of it as a crime.  They may not realize it’s a crime, or they may not know how to handle it if they find out it’s a crime.
assistant
whats so bad about assault?
user