Try learning about some simple sorting algorithms and implement them in python. Most algorithms resources have pseudocode and python conveniently resembles pseudo code in a way. You can just use wikipedia's page on sorting algorithms[0]. You could kill two birds with one stone by sharpening your python skills and get a nice intro to algorithms.
Then maybe try implementing some of the fundamental data structures such as queue's and linked lists[1] along with their basic operations (such as push and pop for queues). Try to see if you can use pythons built-in data structures[2], or do it yourself with object oriented programming.