Sometimes, when we use transitive verbs, e.g.: есть (to eat), пить (to drink), знать (to know), выучить (to learn) – we can use the following counter words as direct objects: много [mnoga], мало [mala], порядочно [paryadachna], достаточно [dastatachna]. As an example, we can provide you with the phrase-clishe: "Он слишком много знал" (He knew too much). As you can see, the notion "много" does not describe here any certain objects (for example, много фактов - many facts, много людей - many people). "Много" (much) - is an abstract notion, which greatly supports the verb "знал" (knew).
Он порядочно выпил на вечеринке - He had a fair amount of wine at the party.
Она достаточно зарабатывает, чтобы путешествовать - He earns enough to travel.
However, these words do not denote a big or small amount, as in the expressions with a noun:
В зоопарке живёт много животных - There live a lot of animals in the zoo.
У него на счету достаточно денег - He has a lot of money on account.
Наша фирма ведёт мало проектов - Our company takes on not so many projects.
"Мало", "много" and "достаточно" are counter words and independent objects here. You can use them without extra words.
Я много работал чтобы понять, как устроен бизнес - I worked a lot to understand the way the business functions.
Я мало путешествовал, и мало видел другую культуру - I traveled a bit and barely saw another culture.
If counter words are used in combination with intransitive verbs, then they are adverbial modifiers, i.e. they denote the way "как" - how - the action was completed - "как много" or "как часто" (how often).
Sometimes, we use the form "многое" instead of "много" with transitive verbs, and the forms "много всего", "много чего" (a lot).
Мы многое поняли за годы учёбы - We understand a lot during these years of our study.
В нашем городе много чего изменилось за десять лет - A lot has been changed in our city.
В мире каждый день происходит много всего - Everyday a whole bunch of stuff is taking place in the world.