The holding is usually described as the answer the court gives to the legal issues it analyzed in the opinion.

For example, in Brown the legal issue is:
Legal Issue: Does segregated public education violate the plaintiffs' 14th Amendment rights?

Then, the holding becomes the answer to that question.
Holding: Yes. The U.S. Supreme Court held that pubic education violates the plaintiffs' 14th Amendment rights.

Of course, you could add the Court’s language, stating that in Brown, it held that:

in the field of public education the doctrine of “separate but equal” has no place. Separate educational facilities are inherently
unequal. Therefore, we hold that the plaintiffs and others similarly situated for whom the actions have been brought are, by reason of
the segregation complained of, deprived of the equal protection of the laws guaranteed by the Fourteenth Amendment. [ ... ] We have
now announced that such segregation is a denial of the equal protection of the laws.