Here's a breakdown of what that means:

* G-type: This refers to the Sun's spectral class, which is determined by its surface temperature. G-type stars have surface temperatures between 5,200 and 6,000 Kelvin (K), giving them a yellowish appearance.

* Main-sequence: This means the Sun is currently in the longest and most stable phase of its life, fusing hydrogen into helium in its core.

So, in essence, the Sun is a middle-aged star, fusing hydrogen and producing energy at a steady rate.