I'm having a hard time understanding how the Magic Initiate feat works; does it require spell slots?
The feat doesn't say the spell cast is free; it only says you can cast it at its lowest level once per long rest. -when you cast it can't cast again - and casting spells normally requires spell slots.
The Way of the Four Elements monk (PHB, p. 80-81) is an exception because it doesn't say you "can cast" the spell, but rather that you spend ki points "to cast" the spell:
You can spend 5 ki points to cast stoneskin, targeting yourself.
You pay ki instead of spell slots.
And rituals are another exception. For instance, the Path of the Totem Warrior barbarian's Spirit Seeker and Spirit Walker features (PHB, p. 50) let them cast those spells regardless, because rituals don't expend spell slots but need to pay with 10 min of casting.
The description of spell slots says (PHB, p. 201):
When a character casts a spell, he or she expends a slot of that spell’s level or higher, effectively “filling” a slot with the spell
The description of the Magic Initiate feat says (PHB, p. 168):
Choose a class: bard, cleric, druid, sorcerer, warlock, or wizard. You learn two cantrips of your choice from that class’s spell list. In addition, choose one 1st-level spell from that same list. You learn that spell and can cast it at its lowest level.
Once you cast it, you must finish a long rest before you can cast it again. Your spellcasting ability for these spells depends on the class you chose: Charisma for bard, sorcerer, or warlock; Wisdom for cleric or druid: or Intelligence for wizard.
Spell slot can cast (PHB, p. 164):
Class Features>Spellcasting>Spell Slots.
You can use the spell slots of those levels to cast the spells you do know
if i'm correct you need to know spell,(to prepare, if you need it), to spend slots to cast, so if you Learn you know or can have prepared?
considering on the 2018 PHB errata, you can't spend spell slots to cast spells from another class.
For instance, the sorcerer errata.
Spell Slots (p. 101). In the first sentence, “your spells” is now “your sorcerer spells.”
but you can cast rituals and spells from your own class, The feat doesn't say the spell cast is free; it only says you can cast it at its lowest level once per long rest.
so i can't spend spell slots to cast spells from another class but can chose it, i can cast rituals because dosen't need spend slots and spells from your own class (if they have) because i can spend it slots, but if i choose nonritual spell from another class i can cast it, but can't spend spell slots and if i can't spend spell slots, virtualy i can't cast it, The feat doesn't say the spell cast is free - requires spell slots.; it only says you can cast it at its lowest level once per long rest. - when you cast it can't cast again
but this statement seems contradictory, observing the fact exists a ritual caster feat, i think miss something.
Does the 1st-level spell you can cast using the Magic Initiate feat need spell slots? Or can you cast it for "free"? What in the text indicates the answer to this question?
Please cite only the rules and those rules only of the PHB to support your answer.