Bind tcp opens up a port on the victim's device. Usually a machine is behind a firewall (or NAT) and firewalls don't allow ports other than a few specific ones (like 80, 443, 22, etc). Reverse TCP tries to connect to you (from the target machine back to you: you open a port and wait for the connection). The attacking machine (yours) has a listener port on which it receives the connection, after which, code or command execution is achieved. If it is remotely, port forwarding should be done on your router.