Your novel has high concept if its basic "idea" can be summed up in a single phrase or sentence. To quote Nathan Bransford's recent blog post What High Concept Means:
"High concept means that a novel/movie/TV show's plot can be described very succinctly in appealing fashion."Do yourself a favour, and read Nathan's blog post through, to make sure you understand high concept. Think through your favourite novels and movies. For each one, decide if it has high concept and if so, what it is. Remember, not all successful novels actually have high concept.
Now, think about your own novel (in progress). Does it have high concept? More importantly, should it have?