The teammate indicator is part of the RPOS system which is implanted into every runners eyes. The indicator gives the position of teammates relative to the runner, and displays useful information like their current health and runner name.
The indicator consists of four important parts through which it is possible to ascertain the status and position of your teammates. The first indicator is the arrow at the top of the box. This shows the position relative to yourself of the runner going by that name. The second aspect is linked to the arrow and allows the indicator to float around the screen, giving a better indication of the teammates position, for example if the runner named "Tom Jeff" is to your right then the indicator will float to the right of the RPOS screen.
The third and fourth parts of the indicator are associated with the name of the runner, and also the amount of health the runner has. The name at the top of the box is obviously the name of the runner in that position. The green bar beneath this shows the relative health of the runner, and can be three different colours dependant on the amount of health the runner has, with the default RPOS colour settings these are green, which shows good health, yellow which means the runner has been damaged, and red which means the runner is on the verge of death. The bar size also changes relative to the amount of health remaining.