My husband's testosterone test result is 23. is it normal?

Cannot tell! Free testosterone or toal. Very low for total but quite high for free! You did not specify!
In ng/dL. If it's in nanograms per deciliter, it's fine. Why do you ask? If he's having erectile dysfunction with normal testosterone, look to relationship issues, prolactinoma or hemochromatosis as possible explanations. If there's some other question, have a joint conference with his physician if you have not done so already.
Lab values. Different labs use different ranges for what is "normal". The value of normal of most labs is also age adjusted. Some people like to have labs that are "normal" and some don't. Labs are important, so are symptoms, desired outcomes, and expected outcomes/results. There are various factors that influence treatment, replacement, and monitoring.