This couplet made me think about delegation more seriously than I normally would. In order to successfully get things done, first you need to understand what needs to be done. In a simple, single word இதனை Valluvar has said "Understand the job that needs to be done in such a way that you are able to succinctly describe to someone else". According to Albert Einstein, If you can't explain it simply, you have not understood it well enough. That's the essence of first word of this couplet.
Now lets look at the second word - இதனால். This word quiet literally translates as "Because", here Valluar in a single word manages to say "articulate your reasons for choosing that person" implying "In order for you to match the job at hand to the right person, you need to have a very good understanding of the level of skill that would be required to compete the job, and the skill level of the potential candidates for the task".
இவன் முடிக்கும் - These words literally translate to "He will complete". Given the value of rest of the couplet and the fact that the Indian society was (and to a great extent is still) patriarchal I choose to overlook the bias towards "male" gender and interpret it as "this person will complete". By saying "this person" what Valluar actually says is "choose": thereby implying "consider more than one option and based on certain criteria select the best person for the job".
The last line அதனை அவன்கண் விடல் - Leave that (job) to that person. The emphasis is on the last word "விடல்" - it translates as "leave". A key part of delegation is to "leave" it to the person you are delegating to. From that point onwards, its that person's responsibility. You don't keep following up every now and then or micro manage. To be able to "leave" it to someone, over and above the understanding of skills, job, as described above, you also need to be able to "Trust" that person.