Ah. A URL.
There are a few things you can do.
If you are on a site in Safari tap the icon that looks like a box with an up arrow. The options are:
1) Add Bookmark: This will save the site's address to your bookmarks (accessed with the book icon in the tool bar). There are several folders and subfolders here, and you can create your own using the Edit button. If you place the bookmark in the favorites folder than the links will also show up on your favorites screen and the favorites tab (if you have it enabled).
2) Add to Reading List. Also using the book icon. It's the tab with the glasses icon.This is a place to put articles and sited you want to read later. The are downloaded for offline reading.
3) Add to Homescreen: This creates an icon on your home screen. It looks just like an application icon, but it will open Safari to the site you've saved. Good for sites you want to visit frequently.
4) Copy: This will place the URL text in your clipboard. You can open any other app with a text entry field, tap-hold for the popup menu, then paste.
Besides these methods you can Message, Tweet, Mail, and possibly use other apps to send or save URLs. In iOS 8 the number of options expands as different apps create sharing and/or action extensions.
Finally, you can tap on the URL bar to select the text there. Tap a second time and you'll get a popup menu with the copy option. Like the other copy method the URL text is stored in the clipboard, and ready for pasting in other apps or text fields.