HEX is a colour model for web graphics.
By specifying the HEX colour code, for example #87b726, you define a certain colour.
A hashtag is a special character.
It looks like this: #
On social media, you write a hashtag before important words.
With a hashtag you can search for information about a topic on social media.
A website host is a person or organisation who owns a website.
This person is responsible for the content on the website.