Nothing can actually repair a damaged hair strand, since they are non-living cells once they leave the follicle, so the only actual fix once the cuticle is physically damaged is a trim with very sharp scissors. However, any product that coats the hair shaft in molecules that will fill in a little of that damaged surface and provide slip will help somewhat with tangling and visible dullness, such as repairing and deep conditioning hair treatments that contain lipids (oils and fats) and/or silicones (dimethicone, trimethicone, dimethiconol, etc.). Silicones can also temporarily sort of glue very small splits together until the next wash, although a split like this one is far beyond their powers.

The down side to silicones is that the way they coat the hair shaft can also keep moisture and lipids out, leading to dryer hair over time, so if you go that route, it's a good idea to use a harsher detergent like a clarifying shampoo once a week or so, followed by some kind of silicone-free lipid treatment, like a shea butter leave-in.

Oils and fats are great for prevention and conditioning! Sebum is a hair conditioner that your body manufactures, and any lipids with similar properties are helpful. You can apply them straight up as an overnight treatment, or use them as a light daily control and protection product, such as by rubbing a little almond oil or shea butter between your palms and finger-combing it through damp hair, although heads up that with hair as fine and straight as OP's it's easy to accidentally use too much and end up looking a bit greasy. Curly, kinky, and thick hair takes really well to heavier use of oils and fats; this is why the Black hair care aisle is shea butter heaven!

For immediate care after a color treatment that incorporates a lifting agent, especially lightening treatments, a protein treatment product like KeraFix can lead to better long-term hair quality by replacing some of the lost protein molecules and keeping the weakened hair from stretching as easily, which does a ton of damage.

And I'll stop there, since this comment is already very long.