A function offers an option. The value of the option decides if elements in a column are aligned right, aligned left or centered. Is it OK to call this option
justify or is only
Align is the correct term.
Think of align as a vertical invisible line running down the page. You can align the text left on that invisible line, right on that invisible line or have the text centered on that invisible line.
Justification is a lateral horizontal measurement based on one of two invisible vertical lines - left and right for justified text or left only for unjustified text.
Whilst the modern terminology seems to suggest
Certainly I've always used
By way of clarification, text within a paragraph is justified, whereas the paragraph is aligned with respect to the margins (etc). In the accounting sense, the numbers are vertically aligned by the decimal points, whereas the currency symbol is usually left justified
The question “Is it OK to call this option justify or is only align correct?” implies that an option name is sought. Both of those words are verbs. Nouns often are more suitable for use as names than are verbs. Noun forms of the words are justification:
It appears that the Collins and Cambridge dictionaries just referenced don't yet recognize special typographical meanings of alignment. Nevertheless, my recommendation is that you use one of the words alignment, positioning, or placement as the name of the option.