What is hit her up?

"Hit her up" is a colloquial phrase that typically means to contact or get in touch with a person, often with romantic intentions. The phrase is commonly used among young people and is often associated with the use of social media or messaging apps, where users can send quick messages or chat with friends. The phrase can be used in a casual or more serious manner depending on the context. It is generally considered informal and may be viewed as inappropriate in a professional setting.