Non native speaker here. The ב represents a 'b' or a 'v' sounds, depending. When the vowels are pointed, you can tell which it is. There are situations where the sounds will change from one to the other. The wiktionary page details the forms of the words for both masc:<pre>
However, I see now that wiktionary disagrees with the audio from duolingo here.
Duolingo audio: something like כַּלְבּוֹת
To confuse matters more, milog.co.il shows something different: https://milog.co.il/%D7%9B%D7%9C%D7%91/e_3195/%D7%9E%D7%99%D7%9C%D7%95%D7%9F-%D7%A2%D7%91%D7%A8%D7%99-%D7%A2%D7%91%D7%A8%D7%99
I suspect there's a bit of variation in spoken Hebrew on this word. I'd love to hear which pronunciation native speakers use.
Well, enter Niqqud in the standard keyboard layout is a nightmare, you have to press three keys combined and have to unlock it after this. I strongly recommend to look for other options, if you are interested in using it often. You may create your own custom layout (e.g. with Microsoft Keyboard Layout Creator, I use this to enter Coptic), you may use a specialised program and copy and paste (I use Shibboleth from Logos Bible Software) or you can buy a programmable keyboard (I use expertkeys, a more expensive solution).