Hi Jazzysweet
Looks to me like you don't want to count all weekdays, but just specified weekdays. You could use the following:
<table style="border: 1.5px solid rgb(166, 170, 182); font-family: Calibri,Arial; font-size: 11pt; background-color: rgb(255, 255, 255); padding-left: 0.25em; padding-right: 0.5em; border-collapse: collapse; color: rgb(38, 34, 48);" border="1" cellpadding="0" cellspacing="0"><colgroup><col style="background-color: rgb(224, 224, 240);"><col><col></colgroup><tbody><tr style="border: 1px solid rgb(166, 170, 182); background-color: rgb(224, 224, 240); text-align: center; color: rgb(22, 17, 32);"><td style="">
</td><td>A</td><td>B</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">1</td><td style="font-weight: bold; color: rgb(0, 0, 0);">Start Date</td><td style="font-weight: bold; color: rgb(0, 0, 0);">End Date</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">2</td><td style="color: rgb(0, 0, 0);">01 January 2009</td><td style="color: rgb(0, 0, 0);">31 May 2009</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">3</td><td style="color: rgb(0, 0, 0);">
</td><td style="color: rgb(0, 0, 0);">
</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">4</td><td style="font-weight: bold; color: rgb(0, 0, 0);">Holidays</td><td style="color: rgb(0, 0, 0);">
</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">5</td><td style="color: rgb(0, 0, 0);">13/04/2009</td><td style="color: rgb(0, 0, 0);">=Monday</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">6</td><td style="color: rgb(0, 0, 0);">09/04/2009</td><td style="color: rgb(0, 0, 0);">=Friday</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">7</td><td style="color: rgb(0, 0, 0);">04/05/2009</td><td style="color: rgb(0, 0, 0);">=Monday</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">8</td><td style="color: rgb(0, 0, 0);">
</td><td style="color: rgb(0, 0, 0);">
</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">9</td><td style="font-weight: bold; color: rgb(0, 0, 0);">Number of Mondays</td><td style="color: rgb(0, 0, 0);">
</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">10</td><td style="color: rgb(0, 0, 0);">21</td><td style="color: rgb(0, 0, 0);">
</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">11</td><td style="font-weight: bold; color: rgb(0, 0, 0);">Number of Mondays (Excluding Holidays)</td><td style="color: rgb(0, 0, 0);">
</td></tr><tr><td style="border: 1px solid rgb(166, 170, 182); color: rgb(22, 17, 32);">12</td><td style="color: rgb(0, 0, 0);">19</td><td style="color: rgb(0, 0, 0);">
</td></tr></tbody></table>
</br>
<table style="border: 1.5px solid rgb(166, 170, 182); padding: 0.5em; background-color: rgb(255, 255, 255); border-collapse: collapse;" border="1" cellpadding="0" cellspacing="0"><tbody><tr><td style="font-weight: bold;">A10</td><td>=INT((WEEKDAY(A2-2)-A2+B2)/7)</td></tr><tr><td style="font-weight: bold;">A12</td><td>=INT((WEEKDAY(A2-2)-A2+B2)/7)-SUMPRODUCT(--(WEEKDAY(A5:A7)=2),--(A5:A7>=A2),--(A5:A7<=B2))</td></tr></tbody></table>