You may have stepped on a tripwire on your way to this sign. Don't worry, you can't take damage in this tutorial.  You might want to go back and look over the area you just came from to see if you can spot the tripwires though.  On the ground in front of you are a few medical kits.  You don't need to use one right now, but you can pick it up.  To use a medpack you just select it like you select a weapon, and if your health is below 100 you will use it.  You can also use it on other squadmembers by putting your mouse cursor over them so it says their name and selecting the medpack.  Keep in mind some characters are better at using medpacks than others, press ~ to see your current character's skills at any time.  Continue along the path to the next Training Area sign.