Much problem. Many problems.
Much problem. Many problems. So grammar. Very wow.
Be nice, Tables, or I'll photoshop you onto a Shiba Inu.
Watno, Grujah: In English the modifiers much and many apply only to collective nouns (mass nouns) and countable nouns (count nouns) respectively. Since problems are countable, you would say "many problems." Problem, singular, is never used as a mass noun, so even "much problem" would be wrong. However, both "much difficulty" and "many difficulties" are allowable because difficulty, singular, is often used as a mass noun.
As far as I can tell, there is no distinction int he Romance languages, but in German this is the different between
viel (much) and
viele (many).
Similarly, little is the opposite of much, while few is the opposite of many. Meanwhile, the opposite of both fewer and less is more; more can refer to either type of noun.