1. Here. This is the most common meaning of koko. It can be used to refer to a specific location, such as "Koko ni kite kudasai" (Please come here). It can also be used to refer to a more general location, such as "Koko wa sekai no naka de ichiban ii tokoro desu" (This is the best place in the world).
2. Now. Koko can also be used to refer to the present time. For example, you could say "Koko wa 2023nen desu" (It is now 2023).
3. This. Koko can be used to refer to something that is close at hand. For example, you could say "Koko no hon wo yonde kudasai" (Please read this book).
4. Own. Koko can also be used to refer to something that belongs to the speaker. For example, you could say "Koko no ie wa watashi no mono desu" (This house is mine).
The meaning of koko can vary depending on the context in which it is used. If you are unsure of what koko means in a particular sentence, you can always ask a Japanese speaker for help.