In the actual assessment, how many questions are there going to be?

It depends on the stage you currently are in the application process.
Initially, there is a test that takes somewhere between 1,5 to 2 hours. It consists of many small tasks which independently can be answered fairly quick.
Next stage is a coding assessment which usually has a few coding questions that need to be completed in 1 hour.
Being successful with this part will send you to the virtual insights day. This will show you what a day in LBG looks like in the span of around 2 hours. You can expect all kind of tasks including recording video answers to some questions. Questions vary in format, but are a bit more challenging than the one in the first test.
Finally, if you have been successful with everything so far, get ready for a full day Assessment Centre, which as much it is challenging, it is just that much entertaining. You get to meet some of our colleagues, get to know more about the group and create some lasting connections. The interviews during the day have different structure and respectively different set of questions and structures, so you can expect as little as just one main question or a set of questions regarding a topic.
If you are successful with this stage too you can expect to receive your offer and begin one fantastic journey with LBG.
One advice I can give is to enjoy the process. No matter how you are doing, try to reflect on your performance and notice where you can improve. This guarantees to cement your further development as a professional.
Good luck!

The virtual assessment centre (the final stage of the application process) typically lasts from 9am - 4pm. During this you will have individual tasks, where you will be given material to read alongside questions to answer, and then have some time to prepare your response and provide feedback. For my VAC (Sustainable Consumer Banking), there was three of these activities. Alongside this we had a group task, which lasted for an hour. This is a great time to showcase your teamwork and collaboration skills. You will also have two individual interview sessions one based on your skills and another on how you align with the role and LBG's values. However, this is to gauge a rough understanding of your knowledge - the interviewers aren't expecting you to be experts! The number of questions will vary from person to person but these each last between 30 mins to an hour so there are quite a few!