I know of muchos, that’s about it. I need to vary my adjectives as i use muchos all the time!
muchos = many
“Tengo muchos amigos”
un montón = a lot
“Tengo un montón de amigos” (literally “a heap”)
You can also use numerosos, abundantes, incontables, depending on the case.
Varios = Many (Tengo varias tareas = I have many chores to do)
Lots = Muchos (Tengo muchos amigos = I have lots of friends)
Una cantidad = Tengo una cantidad de cosas por hacer (I have a big amount of things 2 do)
Miles (a thousand) = hay miles de personas = There’s like a thousand people
millones (millions) = SAme but with millions
muchísimos (lots and lots) = Recibí muchísimos correos (I received lots and lots of mails)
All I can say; stick with it and practise.It is not something you can learn in a few weeks,months or even years.To learn ones native language with limited vocabulary may take 10 years others do not come easier.
many and a lot of means mucho,
you can say too
harto = harto jugo ( too much juice)
abundante = abundante pasto ( a lot of grass)
varios, un chingo(slang).