Let's break that down:

* Main sequence star: This means Altair is currently fusing hydrogen into helium in its core, like our Sun. It's in the most stable and longest phase of a star's life.

* Spectral type A7: This classification tells us about the star's surface temperature. A7 stars are white-ish, with surface temperatures around 7,500-8,000 Kelvin.

* V: This indicates that Altair is a dwarf star, meaning it's relatively small and dense compared to giant stars.

So, Altair is a relatively young, hot, white dwarf star that is currently in the main sequence stage of its life.