Hi I just installed my Pi according to this tutorial https://www.youtube.com/watch?v=4Fe1C1D5DhU but I got just one MacBook so as I put the SD card back, it shows this error The disk you inserted was not readable by this computer.Can you help me what to do please?
macOS can't (it could but won't) read Linux formatted disks.
I don't know what you did (youtube is a no go area) but if you installed by any of the recommended methods https://www.raspberrypi.org/downloads/ it should work if you put it in the Pi.
I also don't know WHY you would install Raspbian Jessie which is about to reach the end of its supported life.
You’ve written your Pi image using an ISO image, which should have an extension ‘.iso’. That’s created the SD card filesystem in a form your Mac can’t read but which your Pi should be able to. So try inserting it into your Pi and see if it it will boot. If it doesn’t and the image is an ISO image then run Disk Utility on your Mac, reformat as an MSDOS FAT disk, check using the first aid tool and then flash the card again using your ISO download