What is your strength means what are the positive aspects you have in yourself that make you a good person? How do you make use of those points while dealing with others and in difficult situations? With this strength, how will you influence and support people at the workplace, and how will you make use of your strengths to do your work in the concern.
An example of strength includes positive thinking, self-respect, self-confidence, my smile, time management (keeping up time or doing things on time), team working, etc. So when strength has so many things to do in the workplace and life, obviously, they would like to know what weakness of yours may affect your growth in life and how your weakness may affect your colleagues, which in turn will result in poor productivity or low performance among people in the company.
The fact is all of us have strength and weakness, so we should never hesitate to speak it out. But when you speak about your weakness, you should explain to them the measures you are taking to overcome your weakness. For example, if you say, "I get stressed out fast when the workload is high," then your answer should be, "Normally, I get stressed out fast due to workload, but now I have started meditating every day for the past 2 months, and I can see that I have good control over my stress; now workload is not a pain for me."
Ultimately, the company wants to know if you think practically and come out with a solution to a problem or if you tend to accept the problems without finding any solution and blame it on your fate, etc.
One should not always live with their weakness even after realizing that it's a negative point in their life. We should be smart enough to convert our weakness into strength.
Hope this information would be of use to you.