A relationship in which one species benefits and the other neither benefit nor harmed

Commensalism

Explanation:

Commensalism is a form of symbiotic relationship in which one species receives the benefit while the second species is neither benefited nor harmed.  

For example –  

Relationships between cattle egrets and livestock  

Cattle egrets eat insects that come out of grasses when animals move, or the insects (ticks, fleas) that attaches to the body of these animals. In this relationship, cattle are neither benefited nor harmed but the cattle egrets are benefited as they get food in this way.