If a cell contains text, return a value in Excel

The standard formula: IF + ISNUMBER + SEARCH

A simple =IF(A2="wireless", ...) only matches when the whole cell is exactly "wireless". To find a word anywhere inside the cell, you need SEARCH.

SEARCH("wireless",A2) returns 1 for "Wireless Mouse M220" because the word starts at character 1. For "Laptop Stand" it returns #VALUE!. ISNUMBER converts those to TRUE and FALSE, and IF picks the result.

Return a number from another cell

The value you return can be anything: text, a number, or another cell. This returns the price when the note mentions a refund and 0 otherwise, so you can total refunds with SUM.

Point SEARCH at a cell instead of typing the word, for example SEARCH($F$1,C2), and you can change the keyword without touching the formula.

Case-sensitive check with FIND

FIND works like SEARCH but cares about upper and lower case, and it does not support wildcards. Use it when "USB" and "usb" mean different things in your data.

Check for one of several words

Wrap one ISNUMBER(SEARCH()) per word inside OR. The cell is flagged if any of them appears. Swap OR for AND when every word must appear.

Count cells that contain a word

If you need a count rather than a label on each row, COUNTIF with asterisk wildcards does it in one cell. The asterisk means "any characters", so "*keyboard*" matches the word anywhere in the cell. COUNTIF also ignores case.

Which method to pick

Need a label or value on each row? Use IF with ISNUMBER and SEARCH. Need it to respect capitals? Swap SEARCH for FIND. Need a single total? COUNTIF or SUMIF with "*word*" is shorter and does not need a helper column. In Excel 365, FILTER can pull out every matching row at once if you want a list rather than a flag.

Whichever you choose, keep the keyword in its own cell and refer to it. Then anyone can change what is being searched for without editing formulas.