Molto can be used as an indefinite pronoun (only in plural), then it has the meaning of many or as an adjective (in singular), in this case the meaning is a lot of. Molto matches in gender and number with the noun it refers to.
A lot of meal is needed to bake a cake.
C'é bisogno di molta farina per fare una torta.
The industrie needs a lot of energie.
L' industria ha bisogno di molta energia.
A lot of coffee is not good for the health.
Molto caffè non è buono per la salute.
Many can' t read. *
Molti non sanno leggere.
I have seen many of them, but no one I liked.
Ne ho viste molte, ma nessuna mi ha piaciuta.
He knows a lot, but he doesn' t speak a lot.
Sa molto, ma parla poco.
Many are just confused.
Molti sono soltanto confusi.
Many (women) are ill.
Molte sono malate.
* We are going to look at the modal verbs in detail later. In all romance languages, and so in Italian as well, there is a distinction between the theoretic ability to do something, because it has been learned and the ability to do something in a concrete moment. If someone is theoretically able to do something because he has learned it, sapere / to know is used.
He can write.
But if he has a broken arm the situation is different.
Sa scrivere, ma di momento no può perchè si è fratturato il braccio.
He can write, but right no he can' t write, because he has a broken arm.
Sapere never can be used for an action which requires no training. This sentence is absurd.
wrong: Lui sa dormire.
Thise sentence is wrong because it suggests that some training is needed to be able to sleep. What really can happen is that someone can' t sleep under certain conditions.
With that noise nobody can sleep.
Con questo chiasso nessuno può dormire.
This sentence is correct as well.
He can read, but right now he is not able to do it, because he has forgotten his classes.
Lui sa leggere, ma al momento non può leggere la tua lettera, perche ha dimenitcato i suoi occhiali.
In some rare cases molto can be used with a noun in singular. But that only happens if the singular is actually a plural, refers to several elements of something.
There are a lot of people in the street.
C' è molta gente nelle strade.
Molto can be an adverb as well than the meaning is very.