Learn Icelandic: Hann kemur frá veitingastaðnum.

The preposition frá (from) always makes the noun following it take the dative case. Veitingastaður (restaurant) is a masculine noun. In the dative case, its definite ending (meaning "the") is -num, which gives us veitingastaðnum.

Wait, what happened to the -ur at the end of veitingastaður?

The -ur at the end of masculine nouns like veitingastaður is only used for the basic dictionary form (the nominative case). When the word changes to the dative case because of frá, that -ur drops off completely. The base word becomes veitingastað-, and then we add the dative "the" ending (-num).

Is veitingastaður a compound word? Does that affect its endings?

Yes, it is made of veitinga (catering/refreshments) and staður (place). In Icelandic compound words, only the very last part of the word changes its endings. Because staður is masculine and becomes staðnum in the definite dative, the whole word becomes veitingastaðnum.

I learned the verb for "to come" is að koma. Why is there an "e" in kemur?