The term host can have several meanings depending on its context.
In general, a host is someone who welcomes and entertains guests, providing food, shelter or other necessities for them. For example, when you say that you are hosting a party, it means that you are organizing the event and inviting people to come over to your place where you will provide refreshments and entertainment.
In addition, host can also refer to an organization or individual who provides internet services, such as web-hosting companies which offer server space for websites. In this context, a user would upload their website files to the hosting company's server so that others can access it through the internet.
The term "host" is also used in biology when referring to an organism that harbors and supports the growth of another organism, known as its symbiont. For example, a clownfish lives among sea anemones which provide protection for them from predators.
In summary, the term "host" can refer to someone who welcomes guests or provides services such as internet hosting, and it is also used in biology when referring to organisms that live together in symbiotic relationships.