I am unable to access Google on my iPhone 5s iOS 8.4

Can you be more specific when you say you "cannot access Google"? Do you mean, that, using Safari, if you try to go to www.google.com, you get that message? Or do you mean something else? Google.com does not require Flash.

Go to Settings>Safari>Clear History and Website Data.

What happens if you use an alternate browser?

It's worth a shot. I don't have any problems accessing the google.com with Safari or Chrome.

Google does not use Flash at www.google.com. In fact, Google avoids flash like the plague that it is. Flash is probably the largest single cause of virus and trojan infections on computers. So if it tells you to update flash you are not on the Google site; your browser has been hijacked.

http://krebsonsecurity.com/2015/06/a-month-without-adobe-flash-player/

http://krebsonsecurity.com/2015/06/emergency-patch-for-adobe-flash-zero-day/

http://krebsonsecurity.com/2015/07/adobe-to-patch-hacking-teams-flash-zero-day/

http://krebsonsecurity.com/2015/07/adobe-to-fix-another-hacking-team-zero-day/

And that's just the past 3 weeks!

Then your router has been hijacked, and is directing you to malware sites. Assuming you are using WiFi and not cellular data.

Well, your iPhone does NOT have Flash, so you are safe from that aspect. If you turn off WiFi can you connect to Google? What about if you use some other WiFi network, such as a coffee shop?

And a key question: Is your iPhone jailbroken?

If you turn off WiFi does the problem go away?

You may not notice it on your other devices if they have flash, but if you go to https://www.google.com on those devices do you get there? And does the address bar in your browser agree that it is https://www.google.com?

.

Go to the Control Center by sliding your finger up from below the bottom of the screen. Tap the WiFi icon to turn it off. Then try again to go to Google.