How do you say hello in British language?

There isn't really a "British language". The language spoken in Britain is English, just like in many other countries.

Here are some common ways to say hello in English, used in Britain:

* Hello - The most common and neutral greeting.

* Hi - More casual and informal.

* Good morning/afternoon/evening - Used depending on the time of day.

* Morning/Afternoon/Evening - More informal versions of the above.

* How do you do? - A more formal greeting, often used in introductions.

Keep in mind that the specific greeting you choose will depend on the context and your relationship with the person you are greeting.