The Minimap is a drawing in the bottom right corner of the HUD which displays the position of teammates, enemies spotted by you or your teammates, and your position and current direction (of both your robot and the ingame camera).
In the controls menu, you can assign a key to make the minimap appear bigger. Pressing it again will return it to it's normal state.
In addition to being able to enlarge the map, while holding E on the keyboard (assuming the player uses the default settings), you can click to spawn a waypoint that will call for help from your teammates. Only two waypoints may be spawned at once and will automatically despawn after a short time. If the player spawns two at the same time, they will not be able to use one again for 10 seconds until the remaining ones despawn. In this mode, Primary click sends a distress signal and plays a siren noise. Tertiary (middle) click tells your team to travel to the location of the waypoint, and plays two soft beeps on use. And secondary click means to guard or defend that location, and plays a ping noise on use.
When in this mode, the minimap is temporarily enlarged, and the mouse is unlocked, preventing the player from turning while in use. Clicking anywhere on the battlefield will spawn a ping or waypoint at that location. Or, clicking anywhere on the minimap will place it at location on the highest point, as if placed from above the map rather than from on the ground. This can sometimes cause misplacement in areas with lots of overhead structures and formations. For example, on Vanguard's End, if someone attempts to place a waypoint in the center of the map and tell everyone to destroy the Protonite Core, the waypoint will instead be placed on top of the Vanguard and away from the core.
These messages are displayed only as drawings, so they can be interpreted in different ways. Generally, in Battle Arena, "go here" is used when someone either needs help capturing an objective, or suggests someone else captures it for them while they help elsehow. And "Stand guard" can also mean to capture a point, though it may depend.