This spell called "lumos" is latin for "lumen". And to translate to english it means "Light".

Another spell to be translated is "Nox" and in latin it fully means "Night". But Nox is also the name of a Roman Goddess of Night derived from Nyx {Greek Goddess of Darkness and Night}. 

Now onto the pronounciation of "Lumos" and "Nox". For "Lumos" pronounciate it as "LU-mohs" and for "Nox" pronounce it as "Nox". It's simple and easy! Practice these words ten times a day just not during your classes. 

To make the light at the tip of your wand brighter, flick it up higher and say the words "Lumos maxima!" It sure brings joy to my heart everytime I do it! (First photo is lumos and secound is Nox)