Muesli is a mixture which contains CEREALS (e.g. oats, wheat, barley) dried FRUIT (e.g. sultanas, raisins, dates) and NUTS (e.g. almonds, hazelnuts).
Here’s an example of a typical British muesli… https://www.amazon.co.uk/Jordans-Natural-Muesli-Kg-Pack/dp/B...
And here’s the Wikipedia entry… https://en.m.wikipedia.org/wiki/Muesli