be on brand with something

[Saki6]

Postcard printing is one of the most versatile and fun ways to market your brand and connect personally with your customers! Just make sure your postcard design is on brand with a clear message and you’ve got yourself the foundations of a successful marketing campaign.​

(5 Real Life Postcard Marketing Strategies)​

Could you tell me what "be on brand with something" means?

 

[teechar]

It means in line with the brand; does not conflict with the brand.

 

[GoesStation]

Or consistent with the established image of the brand.