When one country sends soldiers to a different country but not very many, it could mean a few things.

One it’s a symbolic gesture.

Two with your own troops on the ground, if they become attacked, you now have an excuse to get fully involved. It’s the pathway from advisors to interventions. In some circumstances this can also cause the enemy to become hesitant to attack areas with known foreign presence

Three gathering intelligence from your own people, gives you a higher degree of situational awareness on the ground.

Four weapons research and development, sending a technical advisors, and observers, to an actual combat situation can give you valuable feedback on methodologies, doctrine, and weapons application.