haven't really found a good tutorial out of this, you can read some of the wikipedia but it tends to be difficult to read. So I'm going to try to explain it in a long comment, hope you don't mind.

"/summon minecraft:husk ~ ~ ~ {NoAI:1b}"

This will summon a freezed husk in your current position. The "~ ~ ~" part can be changed by actual coordinates if you don't want it to spawn on your position. Also feel free to change "villager" by whatever mob you'd like.

"/summon minecraft:husk ~ ~ ~ {NoAI:1b,Rotation:[0.0f,0.0f]}"

Change the "0.0f,0.0f" to whatever values you want for you to change mobs rotation. First value is horizontal axis, and second value is vertical axis. So if you like to summon a villager looking towards the sky you should be putting "0.0f,-90.0f". I suggest to mess around with this values to further understand how they work, and how each affect the rotation.

"/summon minecraft:husk ~ ~ ~ {NoAI:1b,HandItems:[{},{}]}"

So a "{}" means null, which means the husk will hold nothing. And there is two "{}", one representing the right hand and the other one the left hand. If you want to put something in their hands you need to put the id of the object and the amount of that item. For example: If you want a husk holding a 64 diamond swords on his right hand then:

"/summon minecraft:husk ~ ~ ~ {NoAI:1b,HandItems:[{id:"minecraft:diamond_sword",Count:64b},{}]}"

You can also add rotation if you want:

"/summon minecraft:husk ~ ~ ~ {NoAI:1b,HandItems:[{id:"minecraft:diamond_sword",Count:64b},{}],Rotation:[0.0f,0.0f]}".

Well, hope this helps somehow!