A more thorough explanation:

Definition: To consent or agree. To be added (to something else) through accession. To adopt. (Of a body politic) to accept unification with or annexation into another body politic.

Examples:

• After much negotiation, the company finally acceded to the union's demands for better wages and benefits.
• Several new countries have acceded to the European Union in recent years.
• The board of directors has decided to accede to the CEO's proposal for a merger with another company.

The first example illustrates the definition of accede as consenting or agreeing to something. The second example shows how something can be added through accession, in this case, new countries joining the European Union. The third example demonstrates how a proposal can be adopted by a group or organization.