You know it's a verb because some sort of action is going on: playing, swimming, running, winning, and countless other 'ings'.

Verbs start in the infinitive. This just means the word 'to' then the verb: to play, to swim, to run, to win. It's said to be split if you put another word between the 'to' and the verb:

To boldly go where no split infinitive has gone before

Once you have the infinitive you can move on and do other things with the verb. You can talk about things in the past:

We played tennis

Or you can talk about what you're doing now:

We are playing tennis

And you can even talk about what you will be doing in the future:

We will be playing tennis

So, past, present, future. These are called Tenses:

Unfortunately, English is not as simple as this. There are also three other tenses you have to worry about: Perfect, Continuous, Perfect Continuous. You can have a Past Perfect, a Present Perfect and a Future Perfect. Same with the other two, they have past, present and future versions too:

If you want to perfect your English, you probably need to dig in and learn this stuff. Native English speakers usually don't bother learning the various names for the tenses. So don't waste your time asking a Native what the Present Perfect Continuous is for the infinitive 'to play'. You'll be met with blank looks. At the very least.

In days of yore, English used to just change the vowels to get a different tense. For example:

Ride Rode
Stand Stood
Drink Drank

However, some past tense endings had a 'hed' sound. For example, 'I love her', 'I lov-hed her'. This 'hed' (ed) sound at the end became the norm for the past tense (no one knows why). What we now know as irregular verbs are words that held out against this 'hed' ending. They held out because they were used regularly. So, irregular verbs are ones that were once used regularly. The 'Rode', 'Stood', and 'Drank' above are survivors. Saying I Roded, I Stooded, or I Dranked just sounded too clumsy or too weird.