Any of the *buntu distros are great for starting out with Linux. Mint is another great distro for Linux newbies too. Very beginner friendly!
If you are trying to get into network security:
Once you have got used to using Linux via whatever distro you decide to get started with; you might want to check out Kali Linux, which is a specialist distro aimed at network security professionals. It has a ton of different tools for auditing network security, penetration testing and forensic analysis.
I usually have a copy of Kali installed on a bootable USB thumb-drive. Has come in handy a few times!
EDIT:
BTW: Welcome to the community!