In an episode of Adriano Olivetti: La forza di un sogno, at the very end, there is an expression that's used just about every day, especially at the end of a conversation, email, a phone call, or text message, so let's have a look.
In this particular case, one person is talking to a few people, so he uses the imperative plural, which happens to be the same as the indicative in the second person plural.
Let me know.Play Caption
Let's take the phrase apart. The verb fare (to make) has been combined with the object pronoun mi which stands for a me (to me). To that is added the verb sapere (to know), in the infinitive.
So, first of all, we might have been tempted to use the verb lasciare (to let, to leave). It would be a good guess, but instead, we use the ubiquitous verb fare: "to make me know." Sounds strange in English, right? But in Italian, it sounds just right. You'll get used to it the more you say and hear it.
Let's look at this expression in the singular, which is how you will use it most often.
The most generic version is this: fammi sapere (let me know).
Va be', quando scopri qualcosa fammi sapere.
OK, when you discover something, let me know.Play Caption
This use of "to make" plus a verb in the infinitive is also used a lot with verbs besides sapere (to know).
Do a Yabla search of fammi and you will see for yourself. There are lots of examples with all kinds of verbs.
Chi c'è alle mie spalle? Fammi vedere. -Francesca.
Who's behind me? Let me see. -Francesca.Play Caption
Sometimes we need to add a direct object to our sentence: "Let me see it."
In this case, all those little words get combined into one word. Fammelo vedere (literally "let me it see" or Let me see it).
Using fare means we conjugate fare, but not the other verb, which can make life easier!