The California State Bar Association, as with any trade organization, is interested in making sure that people who are not members of the Bar do not charge for providing services a bar member might. So you can help anyone you want as long as you do not charge them. There is a logical, good reason behind the prohibition: attorney's in general are much more knowledgeable and wiser than lay people when it comes to legal matters, and when they act really badly the Bar can punish them, which it can not do to lay people.
There is a very unclear line between legal and non-legal work. A court brief is clearly legal work, a settlement or demand letter that does not cite case law nor make it seem that an attorney must have prepared it likely does not have to be prepared by an attorney. So the answer to your question is "yes, no, maybe".
