“Wow, this is actually pretty good.”

You bought a bottle of wine on sale for only $4. You try it out, and are surprised that it's better than you thought it would be. You say:

Wow, this is actually pretty good.

Wow

Saying "wow" shows that you're surprised.

You may imagine that people always say "Wow" in a really excited and energetic way, but you can also say it in a relaxed and calm voice. The example sentence above could be spoken calmly, because it's not that surprising for the wine to be good.

(something) is actually (something)

You use the word "actually" to say that something is different than you expected it to be. In the example above, you didn't expect the wine to be very good.

Here are some more examples of how "actually" is used in a sentence:

Luke found out that Darth Vader was actually his father.

Most people don't know that famous musicians actually don't make much money for their first two or three albums.

pretty (adjective)

The word "pretty" is used before an adjective. It expresses how much of a quality something has. It means "more than expected" or "more than usual". Examples:

I'm pretty tired. How about you?

Food is pretty expensive in New York.

(food/drink) is good

Food and drinks are most often described as "good", rather than "tasty" or "delicious". These words are used as alternatives, when you want to say something more than just "good".