The text makes no explicit explanation of the name Abel. The hebrew name Havel comes from the verb haval that means carefree and is used in the book of Ecclesiastes also with the meaning of vanity, emptiness (see e.g. Eccles 1). So the name Abel give us a sense of freshness. To be a keeper of sheep is perfect for a person like Abel. The job of Cain is something of very different.
In the previous chapter, the soil – in Hebrew adamah – had been cursed because of Adam and Eve’s transgression. Dealing with the cultivation of the soil, Cain experiences all the frustration of the effort that he puts in tilling the ground and the fruit that he gets (see Genesis 3:17-18). So Abel has a job better than that of Cain. It is also well known the old disagreement between farmers and herders. The farmers grudgingly endured the presence of flocks in the vicinity of their camps because sheep often grazed in the plantations. If the etymology of the name Cain indicates a strong man, rough and involved with the thankless job of fields, Abel etymology indicates instead freshness, freedom and happiness. All of this represents a potential conflict ready to erupt!