Learn Russian: Копейка — это деньги.

In Russian, the present tense of the verb 'to be' (am, is, are) is usually left out. When defining what something is (like 'A is B'), Russians often use a dash followed by the fixed word это to link the two ideas. You can think of it as 'A kopeck — this is money.'

Why didn't we use эта to match the feminine word копейка?

When you use это to mean 'this is' or 'it is' to introduce or define something, it never changes its form. You only change the ending to match a noun's gender when 'this' acts as a descriptive pointing word attached directly to the noun, like эта копейка (this kopeck).

I noticed деньги ends in -и. Is 'money' plural in Russian?

Yes, exactly! Unlike English where 'money' is treated as a single uncountable thing, the Russian word деньги is always plural.

What exactly is a копейка?

A копейка (kopeck) is a small Russian coin. Just like a penny is one-hundredth of a dollar or pound, one копейка is equal to one-hundredth of a ruble.