When mixing audio we control how much of the different frequencies in any given sound/sample we use in our productions gets heard with volume, filters/eq’s and different effects. Basically shaping different sounds to sit better together in the mix. We attenuate (lower/remove) how much low frequencies (30-200hz) in say a snare sample gets reproduced so that those frequencies doesn’t amplify the same frequencies in other (i.e a kick) samples, causing the total output of i.e 50hz to overload and unintentionally distort.
The final channel/track in which all of the sounds in your DAW gets sent through before hitting the converters (the chips) in your soundcard. Your sound card converts the signal coming out of your DAW (1s and 0s / binary signal that all computer files are made up of) into electrical vibrations that gets sent to our speakers and gets reproduced as sound.
Hope that cleared up something. I know the wording and technical terms/explanation might not be perfect but hopefully you get the picture.
Here are a few videos on the basics of mixing. Youtube is filled with good material on this subject, and I encourage you to try to find as professional explanations on this subject as possible - as this will help you more quickly get a grasp of the basic terms (not to say that the mumbling FL-tutorial guys can’t teach you a thing or two, but you often end up with more questions than answers in the long run)