Here is a non-exhaustive list of my skills
Correct use of the functions IF, VLOOKUP, LEN, LEFT, LEFT, LEFT, RIGHT, MID, DATE, TEXT.
Complete control of filters
Use of simple conditional formats (usually to highlight error checks)
Creation of graphs and ability to manipulate the axis as desired
A basic understanding of the Excel data model (values vs. presentation, dates are represented by numbers)
Chain of various functions to create a complex formula
Use of more complicated functions (SUMPRODUCT, INDEX/MATCH, raster formulas)
Pivot tables