In XGtE the Ranger Archetypes are awarded additional spells at specific levels.
For example the Monster Slayer archetype receives Protection from Evil and Good at 3rd level. XGtE states The spell counts as a ranger spell for you, but doesn't count against the number of ranger spells you know, so this would mean the a third level Monster Slayer would know Protection from Evil and Good plus three spells.
Does this mean that they still only have three spell slots to use, they have an extra spell slot, or can they cast Protection from Evil and Good without expending a slot?
The way I interpret the rule is that (in the above example) the Monster Slayer knows three spells plus Protection from Evil and Good, but still only has three spell slots to use.