Learn Russian: Те дома очень высокие.

Те is the plural form of тот (that), so it means "those". Эти is the plural of этот (this) and means "these". Since the sentence is about "those houses", we use те to show they are further away.

Since дом (house) is a masculine noun, why does its plural form дома end in "-a"?

The word дом is an exception to the normal plural rules. Instead of adding -ы, it takes a stressed -а in the plural. A few other common masculine nouns do this too, such as город (city) becoming города and глаз (eye) becoming глаза.

Why does высокие (tall) end in -ие instead of the usual plural adjective ending -ые?

This happens because of a famous Russian spelling rule. After the letter к (and a few other consonants like г, х, and ж), you cannot write the letter ы. Because the adjective stem ends in к (высок-), the ending must change from -ые to -ие.

Where is the verb "are" in this sentence?

In Russian, the present tense of the verb "to be" (am, is, are) is almost always left out. The sentence is perfectly complete without it, translating literally as "Those houses very tall."