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I've come across with the phrase below:

I often have a craving that goes something like this: “I want to eat
tacos.”

I searched online dictionaries but I couldn't find any meaning for it.

So could you please tell me what the meaning of "It goes something like this" is?

The full text is:

Every behavior has a surface level craving and a deeper, underlying
motive. I often have a craving that goes something like this: “I want
to eat tacos.” If you were to ask me why I want to eat tacos, I
wouldn’t say, “Because I need food to survive.” But the truth is,
somewhere deep down, I am motivated to eat tacos because I have to eat
to survive. The underlying motive is to obtain food and water even if
my specific craving is for a taco.

Atomic habits by James Clear

Longman defines something like as an approximation:

something like not much more or less than a particular amount

The phrase can be used quantitatively:

The house costs something like forty thousand dollars.

which would mean:

The house costs about forty thousand dollars.

When we use the phrase with the word this, we mean that what follows may not be exact. For example, I might say:

The patient went into a rant, and it went something like this: Why aren’t you giving me my medication? I want it now!

By using “something like this,” I’m admitting that I may not be giving an exact quote, or that I might not be impersonating her mannerisms or voice with 100% accuracy.

In the case you quote:

I often have a craving that goes something like this: “I want to eat tacos.”

I would interpret that to mean that the craving is more of a feeling than actual words, but the person is trying to put that feeling into words. Because the person has never heard words when having his craving, he explains it by saying it goes something like this.

A paraphrase might be:

I often have a craving and it’s sort of like my stomach is saying: “I want to eat tacos.”

You would use the phrase when you wish you could say something more exact than you’re able to do. That’s why (as another answer mentions) it’s often used with music, because most of us can’t carry an exact tune.

We use the expression "it goes something like this" to introduce a short, vague or incomplete description or account of something, or a plan which is subject to modification ("Something like" denotes an approximation, as J.R. notes below).

For example, I am telling you about my plan to to rob a bank. It goes something like this: you wait in the car while I go inside the bank. I produce a gun and threaten the cashier, who hands me some money. I rush outside and into the car, and you drive away very fast.

Another very common use is when asking someone to identify a tune: Person A: I heard a tune the other day - it goes something like this: (sings) la-la-la-LA-LA-la-la-la. Person B: that's "Bohemian Rhapsody" by Queen!

The writer is describing a situation in which he experiences a craving for tacos. he does not actually hear a little voice in his head saying "I want to eat tacos!". The introductory phrase makes that clear.

The verb "go" used here ("it goes something like this") is used to mean "be expressed" ("it is expressed approximately like this"):

go

verb

(BE EXPRESSED) ​

B2 [ I not continuous ] to be expressed, sung, or played:

I can never remember how that song goes.

"Doesn't it go something like this?" said Joan, and played the first
couple of bars on her guitar.

[ + (that) ] The story goes (= people say) (that) he was fired after
he was caught stealing company property.

A headless ghost walks the castle at night - or so the story goes (=
so people say).

Go (Cambridge Dictionary)