The block returns the value of analog pins available in the connected hardware. Analog reading is of 10-bit resolution, hence the range of value is 0 to 1023. This range is mapped to the voltage of the pin (normally 0 to 5V). If the value received is 512, the voltage value will be around 2.5V.
A reporter block is a block that contains a value. These blocks can contain anything, from numbers to strings. Boolean Blocks are a special form of reporter blocks that report either “true” or “false”. To quickly view the value of a reporter, simply click it in the editor and a bubble will display the value.