In what instances would I use “lo que” rather than “que”?

I am learning Spanish and sent my boyfriend a picture of what I was wearing along with a text saying “Este es que yo uso”. He said it would be better to use “lo que” instead of “que”. Can anyone else explain why this usage would be better, and what scenarios are better to use “lo que” and what scenarios are better to use just “que”?

submitted by /u/IntoWaves
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