The first one is a "heat dropper," a mode in which the user can click or drag the mouse to add or remove heat from the location in the model that the mouse points to. If you have a touch screen, you can touch or swipe your finger across it and the heat dropper works as if your finger could give heat to the virtual space in the simulation. The first video in this blog post shows how it works.
The second one is a "field reader," a mode in which the user can move the mouse to read the value of a property distribution field at the location the mouse points to. Currently, the supported property fields include temperature, thermal energy, and fluid velocity (which will be zero in a solid). The second video shows how it works.
If a web page that embeds an Energy2D applet doesn't already have a drop-down menu on the page for you to switch to these modes, you can always access them through the View Options dialog window. The View Options menu can be found if you right-click on a spot in the simulation window that is not occupied by a model component (like a polygon or a sensor).