Go to the queue and notifier palettes, place one of the functions on the diagram, right click it and select Help. You will see a detailed explanation. There are probably also examples in the example finder (Help>>Find Example).
For a quick explanation - a queue is like a line of people at the bank - you can put as many people as you want in it, and when the teller is ready, the person standing in the front leaves the queue. In the same way, you can put elements into a queue in several areas of your code and extract them later one at a time.
This is useful, for example, if you are getting data faster than you can process it - you can put it into a queue and process it when you have the time.
A notifier is used to synchronize different parts of your diagram. It's like several people standing around waiting for someone to call out and then all doing something together.
To learn more about LabVIEW, I suggest you try searching this site and google for LabVIEW tutorials. Here, here, here, here and here are a few you can start with and here are some tutorial videos. You can also contact your local NI office and join one of their courses.
In addition, I suggest you read the LabVIEW style guide and the LabVIEW user manual (Help>>Search the LabVIEW Bookshelf).
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