The most important thing is to find the cleavage site of the enzyme correctly, that is, the specific base sequence. If there is no cleavage site of the enzyme, then the enzyme cannot act on DNA molecules.

If it is a circular DNA molecule with several restriction sites, it will be cut into several fragments.

If it is a linear DNA molecule, (N+ 1) DNA fragments will be formed when N kinds of enzymes (all with restriction sites) are excised.

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Correction upstairs:

In DNA molecules, the bonds between bases are hydrogen bonds, not valence bonds. Breaking hydrogen bonds does not require enzymatic digestion at all.

This enzyme cleaves the 3', 5'- phosphodiester bond between the phosphate group and deoxyribose, rather than any hydrogen bond.

Personally, I did genetic engineering in graduate school.

Landlord, if there is anything you don't understand, please feel free to ask questions.