I have a Strange Cube

[marosaco]

I study Complete Blender Creator: Learn 3D Modelling for Beginners.

In lecture 2, I made a pillar. There is a something wrong.

How to remove? actually what is that?

Thanks in advance

[NP5]

Well First thing is there is double geometry there.
There are face dots in the middle of edges, showing a compressed face on top of an edge.

So fix that first.
Select all with A.
Then press M, Select By Distance.
Then let’s see how that affects it, always possible the main issue is then solved.

Oh and tick ‘clipping’ in the mirror modifier.

[marosaco]

Thanks! It works. I had to remove half of pillar to use mirror again.

Have a nice day NP5!