Hi Hanyue Li,
These words are close in meaning and are best understood in context, but I will give it a try.
Verbinding: a (physical) connection, like two things that are connected. Is also used in the case of a less physical signal like 'de internetverbinding'. It is also used in chemistry when speaking of a chemical bond between elements.
Verbintenis: an older/less common word concerning a connection between two people, for instance because of a contract or marriage.
Verband: a (not physical) connection, so when the meaning of two things are related, or there is an association or causation (e.g. er is een verband tussen auto's en CO2-uitstoot).
Verbond: an agreement between people, for example forming a union, collaborating or deciding that you will share your secrets with each other.
Hope this helps!