How can I put a Google map into a slide?

Go to Google maps, and look for the address you want to show. Then click on the menu icon in the top left next to the searchbox, and click on Share and embed map. Choose Embed map and copy the iframe code. It will be something like the code you can see here:

<iframe src="https://www.google.com/maps/embed?pb=!1m14!1m8!1m3!1d2686.201067203608!2d17.6327019!3d47.680515!3m2!1i1024!2i768!4f13.1!3m3!1m2!1s0x476bbff067c5bc01%3A0x5614666fbf541a35!2zS8OhbHbDoXJpYSB1LiAxLCBHecWRciwgOTAyNA!5e0!3m2!1sen!2shu!4v1415616034067" width="600" height="450" frameborder="0" style="border:0"></iframe>

and what you need from here is the link of the src:

https://www.google.com/maps/embed?pb=!1m14!1m8!1m3!1d2686.201067203608!2d17.6327019!3d47.680515!3m2!1i1024!2i768!4f13.1!3m3!1m2!1s0x476bbff067c5bc01%3A0x5614666fbf541a35!2zS8OhbHbDoXJpYSB1LiAxLCBHecWRciwgOTAyNA!5e0!3m2!1sen!2shu!4v1415616034067

Put down an iframe item into your slide, paste this link into the iframe url, and you are done.