Why the category of CW-complexes is not stable?

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I am studying homotopy theory and I would like to understand better what it means for a category to be stable.

For instance, the book I'm studying says that

"the categories CW∗ and CCh+ have very similar homotopical properties. On the other hand, there is a primary difference between them: while in both we have canonical reduced suspension functor Σ and loop space functor , the cochain complex are “stable” under these functors while CW-complexes are not",

where CW∗ is the category of CW-complexes and CCh+ is the category of cochain complexes over some communtative ring.

I don't know a lot about classical algebraic topology (I went directly to the higher categorical approach). Thus, it would be quite helpful if someone explained the above statement to me.