Learn Russian: Троллейбус и трамвай — это транспорт. - The trolleybus and the tram are transport.

In Russian, the present tense of the verb "to be" (am/is/are) is usually skipped. When linking two nouns to say what something is, Russians often use a dash in writing to stand in for that missing "are".

Since there are two vehicles (trolleybus and tram), why is это singular? Shouldn't it be a plural word for "these"?

When used to define what something is (like saying "X is Y" or "X and Y are Z"), the word это acts as a fixed connecting word. It doesn't change to plural even when talking about multiple things. It just means "this is" or "these are" in this context.

Why is транспорт in the singular form if we are talking about two different vehicles?

Just like the English word "transport", транспорт is an uncountable noun. You don't need to make it plural; the single category covers both the tram and the trolleybus.

How can I tell the gender of троллейбус and трамвай?

Both are masculine nouns because of their last letters. Троллейбус ends in a standard consonant (с), and трамвай ends in the letter й (short i), which is another common ending for masculine words.