My friend sent me a text message on imessage of Apple iphone, but what if I can't get a text message on my Android phone?

Android phone can't receive iMessage? Text messages.

iMessage？ Can only be sent and received between ios devices. It takes the apple id account channel bound by ios devices, not the carrier channel. Using data traffic itself is free.

IMessage information is text, photos or videos sent to another iPhone, iPad, iPod touch or Mac through Wi-Fi or cellular data network.

Extended data:

Regarding iMessage messages and SMS/MMS messages, why are some message bubbles blue or green?

IMessage information is text, photos or videos sent to another iPhone, iPad, iPod touch or Mac through Wi-Fi or cellular data network. This information is usually encrypted and displayed in blue text bubbles. To turn iMessage messages on or off, go to Settings > Messages.

If you don't use iMessage information, you can use SMS/MMS. These messages are texts and photos sent to other mobile phones or other iPhone, iPads or iPod touch. SMS/MMS is unencrypted and appears in a green text bubble on the device.

APPLE Support-Information about iMessage and SMS/MMS