JSFiddle - React, Tailwind, and code Playground

HTML

<table ng-app="testApp" ng-controller="testController">
    <tr ng-repeat-start="(key, val) in testData">
        <td rowspan="{{val.length}}">{{key}}</td>
        <td>{{val[0]}}</td>
    </tr>
    <tr ng-repeat-end ng-repeat="value in val.slice(1)">
        <td>{{value}}</td>
    </tr>
</table>

CSS

table, th, td {
    border: 1px solid black;
}

JavaScript

angular.module('testApp',[])
.controller('testController',function($scope){
    $scope.testData={
        key1:[1,2],
        key2:[3,4,5]
    };
});