Can she follow a pattern? If so, she could find one that suits the yarn she has by looking on Ravelry.
She can filter by yarn weight and difficulty level, as well as other factors, and can see what the finished result would look like on people of all shapes and sizes if they have uploaded photos.
Alternatively, she could search by the yarn itself, and see what other people have knitted in it, or you could do this for her and suggest the pattern to her.
If she can't follow a pattern, maybe a jumper is a bit ambitious when she has nobody to help her; but if she's set on the idea, oversize ones with narrow sleeves are popular (check out 'Boxy' on Ravelry) and she could achieve that look by making two rectangles sewn together, and adding simple sleeves, bearing in mind that the body of the jumper will be very loose, so the sleeves will start at roughly the elbow. The Boxy pattern is probably too advanced for a beginner, as it incorporates short rows to shape the neck - your friend might be better with a simpler slash neck.