bond - How can placing a lone pair in axial position differs from that in equatorial in number of electron domains?

I need help understanding the following statement in my book (regarding trigonal bipyramidal geometry):

Placing a lone pair in an axial position would put it at 90 degree to three other electron domains. Placing it in an equatorial put is at 90 degree to only two other domains, thus minimizing the number of strong repulsive interactions

What does it mean by "90 degree" to two/three "domains"?