Here are some examples:
* "We have an in-house design team": This means the company has its own designers, rather than hiring them from outside.
* "They created the marketing materials in-house": This means the company made the materials themselves, instead of hiring an advertising agency.
* "The training is conducted in-house": This means the company provides the training for its employees itself, instead of outsourcing it to a training company.
Essentially, it implies that the company has the resources and expertise to handle a particular task internally.