The answer is, as so often, "it depends".
Usually directories directly under
/home are only user home directories. It is entirely possible to put other stuff there too, and it won't harm anything.
Whether a user can access a directory under
/home/thisdir, will depend on what permission the directory has. If you grand read and execute permissions only to the owner, then only that owner and root can look inside it. If you grant read and execute permissions to everyone, then everyone can look inside it.
The same goes for users' own home directories. If you have username
avinash, and your home directory is
/home/avinash, then it's up to you to decide who may look inside it. You may choose to have it sealed up so that only you have read and execute permissions - then nobody other than yourself (and root) can read it. Or you may decide that everyone may look inside it - in which case they can.
There's a long description of various file and directory permissions at wikipedia - I think you'll find most of your questions answered by reading it.