Due to some issue in Salesforce lightning css, helpText is not displaying properly in lightning out. Using following styles in your visualforce page, you can display the helptext properly.

CSS:

<style>
        .slds-popover {
        position: relative;
        border-radius: .25rem;
        width: 20rem;
        min-height: 2rem;
        z-index: 6000;
        background-color: #fff;
        display: inline-block;
        box-shadow: 0 2px 3px 0 rgba(0, 0, 0, .16);
        border: 1px solid #d9dbdd;
        font-family: 'Salesforce Sans',Arial,sans-serif;
        }
        
        .slds-popover__body,
        .slds-popover__footer,
        .slds-popover__header {
        position: relative;
        padding: .5rem .75rem;
        word-wrap: break-word;
        }
        
        .slds-popover--tooltip .slds-popover__body,
        .slds-popover_tooltip .slds-popover__body {
        font-size: .75rem;
        color: #fff
        }
        
        .slds-popover--tooltip,
        .slds-popover_tooltip {
        width: auto;
        max-width: 20rem;
        background: #16325c;
        border: 0;
        }
        
        .slds-nubbin--bottom-left:before,
        .slds-nubbin_bottom-left-corner:before,
        .slds-nubbin_bottom-left:before {
        width: 1rem;
        height: 1rem;
        position: absolute;
        transform: rotate(45deg);
        content: '';
        background-color: inherit;
        bottom: -.5rem;
        margin-left: -.5rem;
        }
        
        .slds-nubbin--bottom-left:after,
        .slds-nubbin--bottom-left:before,
        .slds-nubbin_bottom-left-corner:after,
        .slds-nubbin_bottom-left-corner:before,
        .slds-nubbin_bottom-left:after,
        .slds-nubbin_bottom-left:before {
        left: 1.5rem;
        top: 100%;
        margin-top: -.5rem;
        }
    </style>