This is the on/off switch that activates a specific DHCP pool for actually handing out leases, and per the description an admin should configure every other parameter of the pool, address range, lease time, options, before flipping this to enabled, since enabling prematurely risks handing out leases under an incomplete configuration. The description also indicates that disabling an active pool discards its current lease-binding information, so an admin temporarily disabling a pool for reconfiguration should expect all currently-leased clients in that pool to lose their bindings and need to re-request addresses once it's re-enabled. For example, an admin adjusting the address range on an active pool with 40 leased clients should recognize that disabling it to make the change will force all 40 clients to obtain fresh leases afterward, not just resume their prior ones.