What does the "Tx" column mean in Electrum?

Question

I found that there is a Tx column. For most of the addresses, the value in that column is 0.

For some addresses with balance greater than zero, it's not 0.

What does "tx" mean in this table?

Answer 1

In the context of Bitcoin, "tx" usually means transaction. In this specific context, it means the number of transactions that involve that address.

It's weird, why there are some addresses with 0 balance have transactions?

A transaction can be receiving or sending Bitcoin. For addresses that were involved in transactions that now have a balance of 0, some transactions spent the remaining funds associated with those addresses.