The number of colors you should use in your brand depends on the specific needs and goals of your business. Typically, it is recommended to use 2-3 colors in a brand's colour palette in order to create a cohesive and consistent visual identity. However, it's important to note that using a limited number of colours doesn't mean limiting the brand's design, you can use different shades, tones, and tints of the same color to create variation. Additionally, it's also important to take into account the psychology of colour and choose colors that align with your brand's message and target audience.

I always keep it to a minimum. You need black and white and probably 2-3 others maximum.