If you are interested in intensive English lessons, I am available to meet as often as you like. Furthermore, I can help you obtain English language materials to help you immerse yourself in the English language.
This to me would be quite clear cut, in many ways. It may well be a student who wants to learn certain verbs and to conjugate them in as many tenses as possible. This would be quite intense and focused. I am sure there are students who want or need intensive sessions to kick start their linguistic skills or indeed to highlight areas they need to improve in order to sit exams or advance to another level.
So intense could be any aspect of language skill. I may have a student who is very good theory and grammar but really wants and finds it very important to hone their speaking skills.