A channel is sort of like a rung on an abacus. All of your counters stay on the rung but you slide them back and forth.

When your counters are mostly on the near (local) side, you're limited on how many more counters can be brought over to your side but you have plenty to send. This is outbound liquidity.

Conversely, when most of your counters are are the far (remote) side, you're limited by how many counters you can send but you can receive many. This is inbound liquidity.