In English we might imagine a dialogue such as this in a group of housemates:
Who will go to the store to buy milk? -I’ll go.
We have a very brief answer. It includes the person who will carry out the task, and the verb “to go.” Anything else is easily inferred.
But in Italian, it’s common to include the place as well, or some other information, as a pronoun. So, the initial question is the same.
Chi va al supermercato per comprare il latte (who will go to the store to buy milk?)
But the answer will probably be:
Ci vado io (I’ll go there). We would not likely say “I’ll go there” in English, but it’s implied.
So, there’s this extra element in Italian, with respect to English: the place. Ci corresponds to “there,” “to that place,” “to the store.”
Here’s an example from Marika’s video about all these particles.
Cominciamo con "ci" più "mi".
Let's begin with “ci” plus “mi.”
"Devo tornare a casa, mi ci porti?"
"I need to go back home. Will you bring me there?”
Captions 17-19, Marika spiega - I pronomi combinatiPlay Caption
Another example, not about a place but about a situation.
Who will take care of this problem? -I will.
Chi si occuperà di questo problema? -Ci penso io.
Ci corresponds to “of this problem,” or “about this problem.”
Italian has these little pronoun particles that say a lot, and they can often be construed to stand for something in English. But more often than not, they stand for some element of a sentence that generally gets left out in English. This makes learning the little words difficult. They don’t seem to correspond to anything.
If you leave them out, and say, for example, vado io, instead of ci vado io, people will understand you anyway, most likely, but little by little, as you use your Italian in real life, you will get the hang of these particles, and include them more and more often in your speech, and your Italian will become more fluent, more "Italian."
There are two parallel paths to becoming more fluent. The first is to listen and repeat, even if you are merely repeating in your mind as someone is speaking. Speaking, even though you know you will make mistakes, is also important. You can’t very well start out speaking perfectly, and communication certainly comes first. Having someone understand you despite all your mistakes is already a win.
The other path is to study and read. Studying can give you those “ah ha” moments when you figure something out, and it can give you some ground rules so you're not completely lost. But studying won’t help you too much in conversation if you don’t follow the listening path. Once you have a rudimentary knowledge of Italian and can communicate, then studying can help you refine your knowledge and skill.