Learn Turkish: Öpmek güzel bir şey. - Kissing is a nice thing.

In Turkish, the dictionary form of a verb ending in -mak or -mek (the infinitive) also acts as a noun. Just like in English where you can say "To kiss is a nice thing" or "Kissing is a nice thing," Turkish simply uses öpmek as the subject of the sentence.

Why is the word order "güzel bir şey" instead of "bir güzel şey"?

In English, we put the article first: "a nice thing". But in Turkish, when you have an adjective (like güzel) and the word bir (a/an) describing the same noun, the adjective almost always comes before bir. So the word order is literally "nice a thing" (güzel bir şey).

Where is the word for "is" in this sentence?

It is implied! In Turkish, the "to be" verb (am, is, are) is often invisible in the present tense for "he/she/it/this". By putting the subject (Öpmek) and the description (güzel bir şey) together, the "is" is automatically understood. (Sometimes you will see the suffix -dir added to the end to mean "is", like şeydir, but it is usually dropped in everyday speech.)