Keyboard shortcuts: Ctrl+C/V/X/Y; Paste special etc.
Formula auditing: precedents; dependents; show formulas; evaluate formula etc.
Data tools: Absolute references; Data validation; Flash fill; Text to columns etc.
Data types: General; Text; Date; Number; Custom etc.
Arithmetic formula: SUM; PRODUCT; SUMPRODUCT; SUMIF(S); ROUND etc.
Text formula: LEFT; RIGHT; CONCATENATE; LEN; FIND etc.
Formatting: Cell types; Header types; Data as a Table; Conditional Formatting etc.
Logic formula: IF; AND; OR; IFS; IFERROR etc.
Lookups: HLOOKUP; VLOOKUP
References: INDEX; MATCH; INDIRECT; OFFSET etc.
Statistics: AVERAGE/IF/IFS; COUNT/A/IF/IFS; VARIANCE; FORECAST etc.
What-if analysis (incl. Goal Seek)
Basic charts e.g. bar graphs; pie charts; scatter plot etc.
Financial: IRR; FV; PV; NPV; CAGR etc.
Get data: from TEXT; CSV; Web etc.
Advanced charts: combo charts; waterfalls; hierarchy charts etc.