Many of the names of people and locations in Genesis 2-4 seem to tell us about their recipients.
It is sometimes suggested that the names indicate the profession of either brother: 'Cain' (possession) needs to possess land for agriculture, while 'Abel' (breath) herds animals.
However, there is some possibility of a connection between the meaning of their names and the subsequent murder. John Byron (Cain and Abel in Text and Tradition, 30-32) notes that ancient interpreters drew the motivation for Cain's murder of Abel out of their names:
In the Hebrew version of Gen 4:2 Cain's name is part of a word play in Eve's cryptic statement made at her first son's birth. This word play is created by her claim to have "gained" (קנה) a man which would have had a poetic similarity to the name Cain (קין). [...]
[Philo] further develops the pun in the Hebrew by declaring that Cain's name means "possession" and then goes on to provide his own etymology of the name: "The first of these two views is figured by Cain who is called Possession, because he thinks he posses [sic] all things" (Sacrifices 1.2). Josephus also notes that the meaning of Cain's name is "possession" (Ant. 1.52) as does Augustine (City of God 15.17). As we will discover in a later chapter, the etymology of Cain's name became important to those who sought to describe him as greedy and the archetype of the rich oppressors of the poor. As with the attribute that Cain was the son of the devil, anything that could be found to explain why he killed Abel was used to help fill out the details of the story.
The naming of Abel is complicated once again by the complete lack of any detail. Abel's birth is described almost as an add-on to that of Cain's, and there is no declaration made about the son by the mother, nor is there any etymology provided for the name as there is with Cain and Seth. In Hebrew הבל means "breath" or "vanity" and is used elsewhere to describe the shortness of human life (Job 7:16; Ps 144:4; Eccl 1:2). But in spite of the lack of an etymology, interpreters were able to extrapolate meaning from Abel's name which in turn allowed them to expand the text with their own interpretations. Thus Josephus says that the meaning of Abel is "nothing" (Ant. 1.52). There is a variant in Josephus which replaces "nothing" (οὐθέν) for "sorrow" (πένθος) and is similarly found in Philo's interpretation of Abel's name (Migration 13.74). [...]
[...] By reading the story this way, exegetes could demonstrate that even the names of Cain and Abel communicated a message about their lives and the way that God works in the world. [...] The accusation that Cain was a greedy grasper is repeated often in conjunction with the details surrounding his crime of fratricide and his subsequent life following his expulsion.