Hi there subjekt, and welcome to Scarleteen, this is definetly a kind of question that you can ask here
From your post, by saying that you are male, if this means you’re a cisgender man and have a penis, then it sounds like the word you are looking for, rather than "mucus", here is "pre-ejaculate" and "ejaculate", you will often see these called by the slang terms "pre-cum" and "cum", too. Or, if you are a man who has a vulva, some people with vulvas ejaculate and the vagina self lubricates - if this is a more accurate description of you, you could call the lubrication “vaginal discharge” also, but you might also like to use the other words from earlier.
With regards to lube, whilst you might provide a lot of your own natural lubrication that works well enough for yourself (which is not abnormal in and of itself at all), it is important to remember that using lube is not only for your own comfort, but also that of a sexual partner, particularly if you have a penis, or perhaps are using a strap-on or toy of some kind, or a finger etc that is entering their anus (which doesn't produce any lubrication of its own) or their vagina. Not only is lube a great way to avoid uncomfortable friction, adding lube can often add extra fun, you can experiment with the different sensations of slipperiness with the different kinds.
You can read more about this here: