Learn Italian: Riceviamo un regalo da Marco. - We are receiving a gift from Marco.

Da is a very useful preposition that translates to from when talking about the origin or source of something. Because Marco is the person giving the gift, he is the source, so we say da Marco.

Where is the word for we in this sentence?

In Italian, subject pronouns like noi (we) are usually left out. The ending of the verb already tells you exactly who is doing the action. The -iamo ending on riceviamo is the built-in signal for we.

What verb does riceviamo come from?

It comes from the regular verb ricevere (to receive). To make the we form, you drop the -ere ending and add -iamo. The -iamo ending is actually identical for all regular verbs in the we form, whether they end in -are, -ere, or -ire.

Why do we use un instead of uno for the gift?

The word regalo is a masculine noun that starts with a standard consonant. You use un for most masculine words, and only use uno when the word starts with a z or an s followed by another consonant.