TFL (Tensor fascia lata) sounds like a coffee right which is @mrs_hawkins_428 favorite drink 🥤
So this muscle originates just a little posteriorly to the ASIS and inserts to the IT band. It’s actions are abduction, flexion, and internal rotation of the femur as well as external rotation of the tibia. So to understand this you must know where the IT band inserts which is gerdy’s tubercle (lateral aspect of the superior portion of the tibia) and this is important because the TFL is near the hip but it assists in tibial external rotation because of the IT band’s insertion point. As you can see it’s not a huge muscle and not a primary mover of flexion, abduction, and/or extension of the hip. Yet it’s a huge component to stabilizing the hip during walking/jogging/running and therefore should be exercised. Most likely you are exercising this muscle without knowing it but it’s important to understand this muscles action because it performs multiple assistive deeds that larger muscles might need assistance in. For example, if your glute med is week most likely the TFL will take over, if your other hip flexors are week the TFL will assist.
Understand your anatomy and you will understand your body ❤️