i heard kh/s, gh/s, th/s...but i don't understand what they really mean by this..i also cloudmin on hashocean.com and i purchased power of 46kh/s but still dont know who power works.

A hash is a function performed by mining equipment as it attempts to find a solution for a block.

**kh/s = kilo hash per second**Since kilo typically means 1000 in SI units, this is an indication of some number of 1000 of hashes performed every second.

**gh/s = giga hash per second**Since giga typically means 1000000000 in SI units, this is an indication of some number of 1000000000 of hashes performed every second.

**th/s = tera hash per second**Since tera typically means 1000000000000 in SI units, this is an indication of some number of 1000000000000 of hashes performed every second.

For example, you rented equipment that generates 46,000 hashes per second. If the total rate for all miners is 1,000,000 million hashes per second, then you have a 4.6% chance of winning each block, and in the long run you will win 4.6% of the blocks.

Assuming you're talking about bitcoin, the total rate for all miners mining on the bitcoin network is about 1164411854 gh/s (that's 1164411854000000000 hashes per second). If you rented equipment that generates 46000 hashes per second and are trying to mine bitcoin with it, you have about a 0.000000000004% chance of finding the next block, and in the long run you would win 0.000000000004% of the blocks if difficulty never changed.

A new block is solved approximately every 10 minutes, and each block pays a bit over 25 BTC for the entire block. Therefore, if you mine in a pool with your 46000 hashes per second you could expect the pool to pay you about 0.00000000438 BTC per month. Unfortunately bitcoins are currently typically only divided to 8 decimal places, and that monthly amount is 11 decimal places. If you round it off to the nearest minimum divisible unit of bitcoin, you can expect to earn 0.0 BTC per month.

i don't like the lottery example, since miners are secure to "win" at some point if they have the correct hashpower(not too small that will require so much time while the diff keep increase) with a lottery not so much

Nope.

Miners are never secure to "win" at all. They are constantly in a race to be first to find a solution for the current block. If they have high enough hashpower, then the odds that they will be first are much higher, so statistically they are likely to "win" more often (just like if you buy more lottery tickets you will statistically be likely to "win" more often), but the "winner" is still a random result out of all the attempts.