What does 250k validator withdrawable from 560k total mean?

At the time of writing, https://beaconcha.in/validators/withdrawals has roughly 250k validator in the "withdrawable" state and 560k in the "active" state.

What does that mean?

Does that mean 250k validator nodes, roughly half of the active validator nodes, joined the queue for full withdrawal? It seems so according to this figment.io document:

"Full withdrawals involve a validator exiting the active validator set. Once the validator has exited the set, their stake and accrued rewards become withdrawable – the stake and accrued rewards will be sent to the validator’s withdrawal address. "

If a validator wish to continue to stake, but take out the rewards ether to sell them, does he/she need to fully exist as an activate validator and after taking out the staked and rewarded eth, re-stake the staked eth?

This is confusing because only 2.6k changed addresses and 320k validator didn't change their BLS address, showing that few have meant to or accomplished the address-change operation needed for reaping the rewards. Naturally, one expects more validators to reap the rewards than fully withdrawing.