Learn Russian: Из-за кризиса половина населения потеряла работу. - Because of the crisis, half of the population lost work.

The word половина (half) is a noun in Russian. Just like in English when we say half of the population, Russian uses the genitive case after fraction nouns like половина, треть (a third), and четверть (a quarter) to show that relationship. Since население is neuter, its genitive form is населения.

Why is the verb потеряла in the feminine singular form? Doesn't the population refer to many people?

In Russian, the verb must agree with the grammatical subject of the sentence, which is половина (half). Because половина is a feminine singular noun, the past tense verb must also be feminine singular (потеряла). It doesn't matter that the sentence refers to many people, nor does the verb agree with the neuter noun населения.

Why do we use из-за for "because of" instead of потому что?

Потому что means "because" and is used to introduce a full clause with its own subject and verb (like "because the crisis started"). When you want to say "because of" followed directly by a noun, you need the preposition из-за. It is always followed by the genitive case, which is why кризис becomes кризиса.

Why does the word for work (работа) end in -у here?