IF YOU want your website to be found by visitors searching for particular words, then those words need to be prominent in your website. These are your Key Words.
If your website is about selling womens fashion clothing, then not only should there be fashion pictures, but also text to include every possible word that visitors might use in a search. e.g. Womens clothing, fashion dress, upmarket wear, female styles, latest fashion, etc.
Don’t forget to include your location or region if you are targeting visitors there. Visitors tend to narrow their search by including state of country.
Key words can be included in the title tag, meta description, headings, hyperlinks, body text, alternate text for images, email address, domain name.
Be careful not to spam your key words. e.g. Fashion, fashion, fashion.
Check your position in Google by searching for sets of your words.