Here are some tips for writing about 2 charts, graphs or tables:
Write one sentence, but introduce each chart separately e.g. "The first bar chart shows..., and the second chart illustrates..."
2. Summary of main points
Write 2 sentences. If the information in the charts is not connected, find one main point or general trend for each chart. If the charts are connected, try to make comparisons.
3. Main body paragraphs
If the 2 charts are completely different (e.g. a graph and a table), write a separate paragraph about each.
If the charts are the same, and show the same information (e.g. 2 pie charts), don't describe them separately; the examiner will want to see comparisons. In this case, you could write one paragraph describing all of the information, but I still prefer to write 2 paragraphs because it makes the essay look more organised.