Mic Level = Small voltages from microphone capacitors Usually around -60dBu > -30dBu You want this low so your microphone signal is not corrupted by noise because they are tiny signals. When using a microphone straight into a camera or mixer you will need Phantom power (48v) or T Power (12v) as well to power the microphone. Make sure you understand the difference between phantom power and t power.
Many microphones require this power to active the electrical resistance in between their diaphragm and back plate. All condenser microphones have this so they can measure pressure of the air waves by how much the reduction in resistance is. The diaphragm and the back plate are tiny and highly sensitive. Being so tiny means the voltages involved are tiny, hence MIC level being different from other levels like LINE.
Your powering options for any input will be beside it and MIC level is called MIC, if your microphone requires phantom power then choose MIC 48+ or PH meaning phantom power. You will soon hear a difference if it is on LINE level because line level is a much stronger voltage.
Mixers will usually have the following settings PH - DYN - LINE. PH being for phantom power at MIC level. DYN is no phantom power for dynamic microphones but is still MIC level. Final one is LINE which is only for other desks or microphones that have already been powered and amplified from another source.
Find out the difference between Mic Level Vs Line Level and also check out how different types of microphones work. The 2 most common types are split into condenser microphones and dynamic microphones.
Read More Below... including mic level vs line level.