Meaning of this class template

what is the meaning of below written code? especially the constructor, how it actually working?

I am just trying to learn from this.

template<class K, class V>
class interval_map
{
private:
    std::map<K, V> m_map;

public:
    interval_map(V const& val)
    {
        m_map.insert(m_map.begin(), std::make_pair(std::numeric_limits<K>::lowest(), val));
    }
}

can any body tell me. thanks in advance