To filter data to include data based on a "contains specific text" logic, you can use the FILTER function with help from the ISNUMBER function and SEARCH function. In the example shown, the formula in F5 is:
=FILTER(...

If you have a list of things (words, substrings, etc) and want to find out which of these things appear in a cell, you can build a simple table and use a formula based on the SEARCH function.
Setup
Suppose you have a...

To highlight numbers less than a certain value, including numbers entered as text like "

To check if a cell contains specific text, you can use the SEARCH function together with the ISNUMBER function. In the generic version, substring is the specific text you are looking for, and text represents text in the...

To filter data in case-sensitive way, you can use the FILTER function with help together with the EXACT function. In the example shown, the formula in F5 is:
=FILTER(B5:D15,EXACT(B5:B15,"RED"))
Which...

To count the number of cells that contain certain text, you can use the COUNTIF function. In the generic form of the formula (above), rng is a range of cells, txt represents the text that cells should contain, and "*"...

To count cells that contain either one value or another, you an either use a helper column then tally up the count, or a more complex single cell formula.
Background
When you count cells with "OR" criteria, you need...

To check a cell for one of several things, and return the first match found in the list, you can use an INDEX / MATCH formula that uses SEARCH or FIND to locate a match. In the example shown, the formula in C5 is:
{=...

To filter data to include only records where a column is equal to one of many values, you can use the FILTER function together with the ISNUMBER function and MATCH function. In the example shown, the formula in F5 is...

To highlight cells that contain one of many text strings, you can use a formula based on the functions ISNUMBER and SEARCH, together with the SUMPRODUCT function. In the example shown, the conditional formatting applied...

To filter a data in an array formula (to exclude or require certain values), you can use an array formula based on the IF, MATCH, and ISNUMBER functions.
In the example shown, the formula in H5:
{=COUNT(IF(ISNUMBER(...

Note: Excel has several built-in data validation rules for numbers. This page explains how to create a your own validation rule based on a custom formula.
To allow only numbers in a cell, you can use data validation...

To test a cell for one of several strings, and return a custom result for the first match found, you can use an INDEX / MATCH formula based on the SEARCH function. In the example shown, the formula in C5 is:
{=INDEX(...

To lookup the latest file version in a list, you can use a formula based on the LOOKUP function together with the ISNUMBER and FIND functions. In the example shown, the formula in cell G7 is:
=LOOKUP(2,1/(ISNUMBER(...

To allow only values that contain a specific text string, you can use data validation with a custom formula based on the FIND and ISNUMBER functions. In the example shown, the data validation applied to C5:C9 is:
=...