From the literal point of view it means, “When you’re in court tell the truth”. But not only in court. Liars get found out in the end so it’s not worth lying. And further: when you tell lies you don’t always remember what lie you told to whom, so telling lies mixes you up yourself and makes life far too complicated.
Yet it isn’t only truth but trust that this commandment stresses. The truth is of course so important that the sages said, “Truth is the seal of the Holy One, Blessed be He” (Talmud Shabbat 55a).
Trust is equally important. It was said about a certain rabbi that not only was he tolerant, wise and understanding, but people trusted him.
Tragically, recent years have brought forth a procession of politicians and public figures who had fame, power and status but couldn’t be trusted.
The prophet Jeremiah says, “Blessed is the man who trusts in the Lord” (Jer. 17:7). God is the role model: people trust Him.
What a blessing it is if there is a human being whom people can also trust. That is part of Imitatio Dei, emulating the ways of the Creator. It’s also part of practical wisdom and it’s good for society.