Learn Swedish: Den där skyskrapan ska bli hundra våningar hög. - That skyscraper will be one hundred floors tall.

It follows the standard pattern for physical measurements: quantity (hundra) + unit of measurement (våningar) + adjective (hög). Importantly, the adjective agrees with the subject of the sentence. Since skyskrapan is an en-word, we use the basic form hög. If the subject were an ett-word like huset (the house), it would be hundra våningar högt.

Why use ska bli instead of ska vara for "will be"?

Bli literally means "to become." In Swedish, when you are talking about something that is being built, created, or otherwise changing its state, you use bli instead of vara (to be). Since the skyscraper is going to become a hundred floors tall once it is constructed, ska bli is the most natural choice.

Why does skyskrapa have an -n at the end after den där?

This is a reminder of Swedish "double definiteness." When you use pointing words like den här (this) or den där (that), the noun that follows must also be in its definite form. Therefore, you must use skyskrapan (literally "the skyscraper") instead of the base form skyskrapa.

I've seen våning used to mean "apartment." Does it mean something different here?