Learn Russian: Что значит это слово?

Russian word order is very flexible. In questions starting with a question word like что, it is very common to put the verb immediately after it. However, saying Что это слово значит? is also perfectly correct.

Why do we use это instead of этот or эта?

The word for 'this' has to match the gender of the noun it describes. Because слово (word) ends in -о, it is a neuter noun. Therefore, we must use the neuter form это.

How would I use this exact phrase in an indirect question, like 'I want to know what this word means'?

You can plug it in without changing anything! You would say: Я хочу знать, что значит это слово. Unlike English, Russian doesn't require any special word order changes for indirect questions.

Is значит related to the word знать (to know)?

Yes, they share the same root! The infinitive here is значить (to mean), which comes from the same origin as знать (to know) and знак (sign). It is a regular type II verb, which gives us the -ит ending for 'it means'.