Accessibility means making a website or app usable by people with different abilities and needs. This can include people who use a keyboard instead of a mouse, listen to a screen reader, or need larger text.
For example, a video with captions can help someone who cannot hear the sound and someone watching in a noisy room. Clear labels and strong contrast can help more people understand a page.
Accessibility is not one feature to add at the end. It is something to consider while choosing words, layouts, and interactions so more people can use the product.