Don't understand the meaning of ''training a dataset''

Hi, I have a set of data. Those data are based on data mining from my website. I have the number of users per month who go to my website ( X ) , and the time they spent on the website on each webpage ( y ) .
Now with this dataset as an example, could you explain to me please what's the meaning of training dataset? If I would ''train'' those data, what should I do? And what is the meaning of the word? A simple example I am noob starting out from somewhere, please. (I know somenthing about linear regression and logistic regression, anyway never dealt with machine learning, if you could make an example with it)


Omega Contributor
I will add some more. If you have a sufficient amount of data, the data science protocol is to randomly split your data into three sets to build, say a prediction, model using the training set while tuning the model's hyper-parameters using the validation set. Lastly you apply the built model to third set to tests it based on a chosen error function (eg, missclassification). So you train, validate, and test a model using the sets.