What are the characteristics capabilities limitations of computer?

Speed, Reliability, Storage Capacity and Productivity
Computers of all sizes have common characteristics -- speed, reliability, storage capacity, and productivity. Computers are the foundation of business, travel, and leisure life today. Computers provide the processing speed required by all facets of society. The quick service we expect at the bank, at the grocery store, on the stock exchange, and on the Internet are dependent on the speed of computers. Can you imagine our world without computers?
Computers are extremely reliable as well. Most errors are caused by humans, not computers. Computers are capable of storing enormous amounts of data that must be located and retrieved very quickly. The capability to store and retrieve volumes of data is at the core of the Information Age.
Speed, Reliability, Storage Capacity and Productivity
Computers of all sizes have common characteristics -- speed, reliability, storage capacity, and productivity. Computers are the foundation of business, travel, and leisure life today. Computers provide the processing speed required by all facets of society. The quick service we expect at the bank, at the grocery store, on the stock exchange, and on the Internet are dependent on the speed of computers. Can you imagine our world without computers?
Computers are extremely reliable as well. Most errors are caused by humans, not computers. Computers are capable of storing enormous amounts of data that must be located and retrieved very quickly. The capability to store and retrieve volumes of data is at the core of the Information Age.
According to basic theory, computers are the modern form of a theoretical computing machine called a Simple Turing Machine. These machines are purely logical - they can perform logical functions like adding and subtracting, multiplying and dividing, and can be made to perform more complex functions like algebra through a series of instructions called an algorithm. They are, however, incapable of logical leaps. They cannot conceive of infinity. They cannot process imaginary numbers (well, they can now, since we've developed the obscenely complex algorithms necessary to make them do so). In short, they can't think like a human can. (Though artificial intelligences these days are good enough that they can mimic human behavior reasonably well, especially if you're applying the upper end of AI theory - on the other hand, they're also very processor intensive, which is why simpler ideas are used where possible). On the plus side, the theoretical Simple Turing Machine concept was developed specifically for high speed computation. In essence, the idea that a computer is a REALLY fast idiot. It needs you to explain everything in near-infinite detail (computer programming), but once you're done, it can process each step way faster than any human possibly could.

If you're wondering, the Complex Turing Machine is basically magic. If a simple turing machine is faced with a dozen choices, one of which is right, and the correctness can only be determined after selecting a choice, it can follow each choice until it is proven wrong, and systematically scroll through the choices until it comes up with the right path. (this is like finding the right path through a maze by taking every path until you get through). A complex turing machine somehow intuitively selects the correct answer each time, thus vastly reducing processing time. It'd be really nice if we could build even one Complex Turing Machine, but I doubt it'd happen.

In summary:

Capabilities of a computer: Can do things really fast.
Limitations of a computer: Can't think intuitively or use abstract concepts like infinity.

what are 3 capabilities of computer

That all depends on the processing power and the hardware installed. You can have a computer which is very simple like a calculator to a supercomputer, please be more specific