Can anyone tell me what this is?

I cant for the life of me find out what this is, I am new to the business and this is the first time I have ever encountered this and I cant get it removed so I am asking for help on what this is and how to remove it.

The brown streaks it seems to only be present on parts of the house that are in the shade a lot and do not get much sunlight, how do I fix these any help will be appreciated.

Exactly, all the brown / yellow is in the shaded areas of the house, the entire back of the house is like this it is very ugly looking, but the sides that have sunlight look amazingly white and clean.

So the only way to fix this is to have the house re-painted I presume since this just comes with age and shade.

I gave you a link to all the information you need to solve your problem. All You have to do is read it.