What does a combust and retrograde mercury mean?

For reference, I am a cancer ascendent and have sun, mercury, mars conjunction in my 2nd H. Jupiter too, is placed in the 2nd H in lagna chart but moves to 3rd H in chalit chart. Mercury and mars are combust but mercury is also retrograde. What does it mean? I also have my mercury mahadasha coming up in 2027.

Very new to astrology, would love some insights.