The term “present participle” sounds odd to me because it can be also used in past tenses. For example, in the past continuous tense. Could you tell me why the term is so called?
[1]
The train to Bath is now approaching platform 3.
[2]
The train to Bath was approaching platform 3.
It's called the 'present participle' because the time associated with it is
characteristically the same as that expressed or implied in the larger construction containing it. For example, in [1] the time of approaching is simultaneous with the time of speaking.
[2] expresses past time by virtue of preterite "was", but there is no change in the form or meaning of "approaching".
'Present' is thus to be understood in a relative rather than absolute sense: the approaching is present relative to the time given in the larger construction.