You know that 思う means "to think" and 出す means "to take out." So this is what happens when your brain takes a moment to think and pulls a memory out of storage. It means to remember!

You can shout 思い出した！when you recall your keys are in the fridge. (Again?!) You can also say 母を思い出します when something reminds you of your mom. In Japanese, you usually omit what reminded you of the memory because the important thing is the memory itself, filling your heart with touchy-feelies. Oh, mama!

The reading for this word is the kun'yomi readings. You should know the words 思う and 出す and their readings, so you should be able to read this word if you know those words.