Here are some common idiomatic expressions in English.
When you mean business, you are serious.
When you mean well, you have good intentions, but you don’t always manage to carry them out.
A means to an end
If something is a means to an end it is not valued in itself but is useful in achieving an aim.
Have the measure of
When you have the measure of someone, you understand their character or abilities.
Mention someone in your will
To mention someone in your will is to leave a legacy to them.
Mess something up
To mess something up is to handle it badly.
To mill about is to move about in a confused mass.
Not mince words
When you don’t mince words you speak plainly.
Be in two minds
When you are in two minds, you are unable to decide between alternatives.
Out of your mind
When you are out of your mind, you are not thinking sensibly.
An expression used to refer to people who are moving to a higher social class.
Make a mountain out of a molehill
To make a mountain out of a molehill is to exaggerate the importance of a small problem.