Yep, I’d agree, sounds like the MAC address table size. So effectively this is the number of devices that the switch can know of from all of its SVIs (Layer 3 interfaces). If you exceed this figure then you’ll experience flooding of unicast packets.
If a client sits the other side of another Layer 3 hop then the switch doesn’t need to know it’s MAC address, only the MAC address for the next hop. So as long as your 5,000+ clients aren’t all using the MS250 as their Layer 3 gateway then you should be fine - if they are all using the MS250 as their Layer 3 gateway then you may hit flooding issues (might be time for a switch upgrade).
EDIT: I think I explained a MAC address table well, but it’s not actually the same as the ARP table that @ww mentions. Since it’s referenced in a Layer 3 document, the ARP table makes more sense as it’s more aligned with Layer 3 - similar but different. If it’s the ARP table then it will still be a limit on clients from Layer 3 interfaces, but might result in extra ARP broadcasts (instead of flooding).
