What does "screw up" mean?

How's it different between "go" and "go down"?

Great question. To "go down" almost always means moving to a lower place, either literally or figuratively. However, there are several usages where the meaning is "away" from the speaker's current location, in that case, the meaning is the same as saying "go". In the video "go down to the store" is being used but "go to the store" would mean the same thing as they both just mean going away from one location to the store. Ex: Let's go down to see grandma this weekend. Ex: Let's go to see grandma this weekend. Ex: Do you want to go down to the beach? Ex: Do you want to go to the beach?

When can I use the expression "tap out"?

"Tap out" or "tapping out" refers to a participant in a fight or boxing match tapping the floor to signal that they are submitting to the other fighter when the other fighter is holding them against the ground. "Tap out" is not a common term used in conversational English, however it could be said to tell someone to submit during a fight, or describe someone doing the action of "tapping out" during a fight.

What does "better off" mean?

"Better off" means to be in a better position, especially financially. You may also hear the phrase "well off," which has a similar meaning as better off, but it really only focuses on the financial aspect. Ex: She is better off financially than I ever will be. Ex: He is better off without her. Ex: We are better off living in a small town than in a large city.

Doesn't the “retrievers” a kind of breed? What does it mean here?

Yes, "retrievers" are a type of dog breed. However, "retrievers" here means that dalmatians are good at "retrieving" things, or getting objects and bringing them back.

What is the difference between "book" and "reserve"?

To "book" something usually implies that something was purchased, while to "reserve" something means it is being saved for you, but you didn't have to pay. Ex: I booked a flight for us to Hawaii Ex: reserved a table for us at a nice restaurant.