Translation:Tim sleeps a lot, and is always late for school.
It's a difficult question. I'll try to explain. Here, school is being used more as an activity, ie the process of taking classes and learning. It's acting as an abstract noun, rather than a definite noun referring to the school building or the school entity. Therefor, you don't use "the."
I saw on Fedor's russian channel that многа was really only for quantifiable nouns, like water or chicken wings, not so much verbs like in "to sleep a lot". Is this correct?
I think спит is the word used when a person who is male/female/neuter does a work. For example-
Male person - том Том живет в европе (notice how it is жив(е)т
Compared to the speaker doing an action: Я живу в Европе (the word живет is changed to живу, much like english's "you are" and "i am" verb declensions
The different declension endings i can recall are-
First person- add eithe у or ю at the last (жизин -> живу) Male/female/neuter- жизнь -> живет мы- живем Они- живут Вы - живете
Sorry for bad grammar but hope this helps!