> OP_CHECKLOCKTIMEVERIFY (CLTV): This opcode allows you to create a transaction output that cannot be spent until a certain time in the future. It is more reliable than nLockTime for future spending conditions.

Every Bitcoin transaction is a script that redefines the permissions required to affect a specific quantity of Bitcoin. When you send the normal Bitcoin transaction, you are not sending Bitcoin to an address, you are telling the network that the signature must match that pubkey for a transaction involving that coin to be valid. You can set other restrictions on valid transactions through other opcodes and scripts.

The reason there's a 65k block limit with CLTV is because this opcode accepts a 16 bit integer value.