What is the type of this transducer?
As with many things in the electronics world, you start by finding a datasheet for the device.

In this case, it doesn't tell you much about how the device works.  It is more about providing information on how it measures up according to standard EN 12668-2.

Slightly more useful is this product page from a company that sells them.

There we learn that your module is an angle beam transducer (which you already knew) and that it has a single crystal.

Both the datasheet and the web site tell you that it operates at 4MHz and has a beam angle of 45 degrees.

It doesn't appear to be a delay line transducer.  That's a feature I would expect to see noted if the transducer had it.  Given the definitions, I'm not sure you can get an angle beam transducer together with a delay line.

A delay line transducer has an additional piece of plastic between the transducer and the outside world.  It takes the ultrasound a known amount of time to traverse that plastic piece.  

Ultrasound works by detecting echoes.  If the echo arrives too soon, then it can't be properly detected.  Things close up can't be "seen" properly so you might miss defects in the top layer of the target.  

The delay line is kind of like a far sighted person holding the newspaper at arms length in order to see it better. 

Since the length of the delay line is known, you can mathematically account for it and remove its length from the measured distance to a flaw.



In any case, your job is to discover the properties of the transducer you were given and see how they would relate to the products you might have to inspect.

In what conditions would an angle beam transducer be of more use than a transducer that isn't angled beam?

When might you want a delay line transducer, and why?

What effect does the frequency have on the resolution?

I'm sure there are a million other details.

You need to get familiar with the transducers and your products, and match requirements and capabilities.

This question is in fact too broad, and will be closed soon. (I will vote for closing it in just a moment.)

I had too much to say to squish it into comments.