In general, the word “consent” can be used in two different ways:

(i) as an uncountable noun – this refers to the concept/idea of consent

The management board must obtain prior written consent from the Shareholders’ Meeting in order to perform certain activities.

Here “consent” means “permission”, “approval” or “compliance” – all of these are also uncountable nouns.

(ii) as a verb – this refers to giving consent

Unless the President of the Management Board consents to the initiative, we cannot go ahead with it.

Here “consent” means “permit”, “approve” or “comply”.

In a business or legal context it is also possible to use “consent” as a countable noun. But this is not normal in everyday English. As a countable noun “a consent” means a document or certificate which provides consent.

So in the below example,  “a consent” is wrong, as we are talking about the uncountable concept of consent. It should be “its consent” or simply “consent”.

The Buyer will not undertake any activities and it will not give a consent to carry out any acts which would preclude the occurrence of the result mentioned above.

However, in the next example, “consents” is correct because we are talking about countable documents.

The Company and the Subsidiaries hold all licences, concessions, permits, consents and certificates required to conduct their core activities.

Usage notes

“Consent” as an uncountable noun
obtain / receive consent from sb.
obtain / receive the consent of sb.
give / grant consent to sb. / sthg.
give / grant sb. consent

sthg. may be done by common consent (i.e. if everyone agrees)

“Consent” as a verb
you consent to sthg.