be under no illusion

US /biːt əˈraʊnd ðə bʊʃ/
UK /biːt əˈraʊnd ðə bʊʃ/
"be under no illusion" picture
1.

no hacerse ilusiones, ser consciente

to understand the true facts of a situation and not have false ideas

:
You should be under no illusion about the difficulty of this task.
No debes hacerte ilusiones sobre la dificultad de esta tarea.
We are under no illusion that this will be easy.
No nos hacemos ilusiones de que esto será fácil.