How do warlock spell slots work in 5E?

The Pact Magic table shows how many spell slots you have to cast your warlock spells of 1st level and higher To cast one of these warlock spells, you must

When regular spell slots are depleted, that's when you can use warlock slots when casting spells learned from other classes From what I read on

warlock s book slot If we convert the Warlock's spell slots into spell points at that same rate, they have a pool of points roughly equal to their level, too

warlocks book slot So, what do all those class features mean? And why does the table list is spell slots, rather than spells per day like most spellcasters? Tune